JP3319405B2 - Discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp, and more particularly to a discharge lamp lighting device for lighting a low pressure discharge lamp.

[0002]

2. Description of the Related Art Fluorescent lamps, which are a type of low-pressure discharge lamp, are widely used due to their high efficiency and long life.
In recent years, taking advantage of its features, it has also attracted attention as an alternative light source for electric bulbs. Also, advanced functions such as dimming are being advanced.

A conventional discharge lamp lighting device of this type is disclosed, for example, in Japanese Patent Application Laid-Open No. 60-157192. The discharge lamp lighting device is configured as shown in FIG. In FIG. 4, 31 is a DC power supply, 32 is a fluorescent lamp as a discharge lamp, 33 is an inverter circuit for supplying a lamp current to the fluorescent lamp 32, and 34 is a capacitor for limiting the lamp current when the fluorescent lamp 32 is turned on. . The inverter circuit 33 includes a constant current inductance 35, transistors 36 and 37, a capacitor 38, resistors 39 and 40, and a transformer 41.

In the above configuration, the output of the DC power supply 31 is connected to the transformer 41 via the constant current inductance 35.
Applied to the middle point of the secondary winding 41a,
The current is shunted to the respective base resistors 39 and 40 and used as part of the bias. The transistors 36 and 37 are alternately switched by the voltage induced in the base feedback winding 41b of the transformer 41, and the secondary winding 4
An alternating current is output to 1c. Secondary winding 4 of this transformer 41
The lamp current is supplied through the capacitor 34 by the AC output of 1c, and the fluorescent lamp 32 is turned on.

Reference numeral 42 denotes a preheating circuit for supplying a heating current to the two filaments 32a and 32b of the fluorescent lamp 32. The basic configuration operation of the preheating circuit 42 is the same as that of the first inverter circuit 33, and includes a constant current inductance 43, transistors 44 and 45, capacitors 46, resistors 47 and 48, and a transformer 49. The output of the DC power supply 31 is applied to the middle point of the primary winding 49a of the transformer 49 via the constant current inductance 43,
At the same time, the respective base resistors 47, 4 of the transistors 44, 45
8 and is used as a part of the bias.

The transistors 44 and 45 alternately switch with the voltage induced in the base feedback winding 49b of the transformer 49, and output an alternating current to the secondary winding 49c and the tertiary winding 49d of the transformer 49. The filament 32a of the fluorescent lamp 32 is attached to the secondary winding 49c.
A filament 32b of the fluorescent lamp 32 is connected in series to d, and a heating current is supplied to the two filaments 32a and 32b of the fluorescent lamp 32 by AC output to the secondary winding 49c and the tertiary winding 49d.

As described above, while the preheating circuit 42 supplies the heating current to the two filaments 32a and 32b of the fluorescent lamp 32, the inverter circuit 33 supplies the lamp current to the fluorescent lamp 32, and the fluorescent lamp 32 Is taught to be able to light stably.

[0008]

However, in the above-described conventional discharge lamp lighting device, the path of the lamp current supplied to the fluorescent lamp 32 via the capacitor 34 is the secondary winding 49c and the tertiary winding of the transformer 49. There are two paths, a path α via the line 49d and a path β not through. The existence of the path α increases the current flowing through the secondary winding 49c and the tertiary winding 49d of the transformer 49, and thus has a problem that the loss and heat generation of the transformer 49 increase.

The lamp current flowing into the two filaments 32a and 32b of the fluorescent lamp 32 flows from the two paths α and β, so that two discharge spots are formed on the filament. This is because the lamp current is shunted, and there has been a problem that the discharge spot temperature is lowered and the extinguishing easily occurs. Especially fluorescent lamp 3
In the case of dimming 2, the discharge spot temperature is further lowered, so that the probability of extinguishing increases, and it is difficult to perform dimming lighting with low power.

The present invention solves the above problems,
An object of the present invention is to provide a discharge lamp lighting device in which most of the lamp current is caused to flow through a path β to reduce a loss and concentrate a discharge spot at one point.

[0011]

According to a first aspect of the present invention, there is provided a discharge lamp lighting apparatus comprising: a power supply having a constant output voltage polarity; and an inverter connected to an output terminal of the power supply. A discharge lamp having a filament at an output end of the inverter circuit, and a preheating circuit for supplying a heating current to the filament, and a voltage of the filament and a voltage of the discharge lamp with respect to an inverter side terminal of the filament. The voltage and the voltage are almost in opposite phases.

A discharge lamp lighting device according to a second aspect of the present invention has a transformer in an output stage of an inverter circuit, and a signal having substantially the same phase as a lamp voltage or a lamp current of the discharge lamp is applied to one winding A of the transformer. And a preheating circuit composed of at least one winding other than the winding A of the transformer.

In a discharge lamp lighting device according to a third aspect of the present invention, a power supply or an inverter circuit having a constant output voltage polarity has a power varying means for the discharge lamp.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a DC power source as a power source having a constant output voltage polarity, 2 denotes a fluorescent lamp as a discharge lamp, and a filament. 2a and 2b. 3 is a DC power supply 1
An inverter circuit 4 is connected to the output terminal of the lamp for lighting the fluorescent lamp 2 and a capacitor 4 for limiting the lamp current when the fluorescent lamp 2 is turned on. In addition, the inverter circuit 3
Is composed of a constant-current inductance 5, transistors 6 and 7, a capacitor 8, resistors 9 and 10, and a transformer 11. Further, the transformer 11 has a winding 1 as a preheating circuit.
1a, 11b, and the winding 11a is a filament 2a
The winding 11b is connected to the filament 2b. In addition, the black circle of each winding of the transformer 11 indicates the beginning of winding of each winding.

The operation of the first embodiment having the above configuration will be described. First, the output of the DC power supply 1 is applied to the midpoint of the winding 11c of the transformer 11 via the constant current inductance 5, and at the same time, the base resistors 9, 10 of the transistors 6, 7 are connected.
And is used as a part of the bias. Transistors 6 and 7 are base feedback winding 11d of transformer 11
, And alternately outputs the alternating current to the winding 11 e of the transformer 11.

The lamp current is supplied to the fluorescent lamp 2 via the capacitor 4 by the AC output of the winding 11 e of the transformer 11. At the same time, the winding 11
An alternating current whose polarity changes in the same cycle as the output of the winding 11e is output from the output terminals a and 11b, and the output supplies a heating current to the two filaments 2a and 2b.

As described above, in the operation of the first embodiment,
The relationship between the polarity of the lamp voltage / lamp current of the fluorescent lamp 2 and the polarity of the voltage generated in the windings 11a and 11b will be described with reference to FIG. The AC output of the winding 11e of the transformer 11, which is the output terminal of the inverter circuit 3, causes the fluorescent lamp 2
The polarity of the lamp current changes periodically. FIG. 2A shows a case where the filament 2a has a higher potential than the filament 2b, that is, a case where a lamp current flows from the filament 2a to the filament 2b.

At this time, in the present embodiment, when the inverter-side terminals A and B of the filaments 2a and 2b are used as a reference, the voltages generated in the windings 11a and 11b and the lamp voltage of the fluorescent lamp 2 are in opposite phases. become. That is, the winding 11
Since the voltage generated at a and 11b is higher on the + side than on the − side, the lamp current is prevented from flowing through the path α,
Most of the lamp current flows in path β.

FIG. 2B shows a case where a lamp current having a polarity opposite to that of FIG. 2A flows. At this time, the windings 11a,
The voltage generated at 11b also has a polarity opposite to that of FIG. 2A, and similarly, the lamp current is prevented from flowing through the path α, and most of the lamp current flows through the path β. That is,
When the terminals A and B are used as a reference, the winding 11
filaments 2a, 2 generated by output voltages of
By making the voltage of b and the lamp voltage of the fluorescent lamp 2 in opposite phases, the flow of the lamp current in the path α can be reduced and most of the current can flow in the path β. Since only the heating current of the filaments 2a and 2b is used and the current value can be reduced, the loss of the windings 11a and 11b can be reduced, and the heat generation of the transformer 11 also decreases. In particular, in recent years, attention has been paid to a light bulb alternative light source using a fluorescent lamp, in which it is essential to reduce the loss in order to reduce the size of the device. In addition, since most of the lamp current flows through the path β, the discharge spot is concentrated at one point, and the lamp can be stably maintained without the lamp going out.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. FIG. 3 is a block diagram showing a second embodiment of the present invention. In FIG. 3, reference numeral 21 denotes a DC power supply which is a power supply having a constant output voltage polarity, 22 denotes a fluorescent lamp which is a discharge lamp, and a filament 22a. , 22b. 23 is a DC power supply 2
An inverter circuit 24 connected to the output terminal 1 for lighting the fluorescent lamp 22 is a transformer, which limits the lamp current when the fluorescent lamp 22 is turned on by the inductance of the winding 24c which is the winding A. Therefore, a current having the same phase as the lamp current flows through the winding 24c.

The inverter circuit 23 is connected to the FET 2
5, 26, a capacitor 27 and an oscillation circuit 28. The oscillation circuit 28 turns on the FETs 25 and 26 and
A signal for F drive is output. Further transformer 24
Has windings 24a and 24b as a preheating circuit and has windings 24a
Is the filament 22a, and the winding 24b is the filament 2
2b. In addition, the black circle mark of each winding of the transformer 24 indicates the beginning of winding of each winding. Also capacitor 2
Numeral 9 is provided for generating a high voltage for starting the fluorescent lamp 22, and generates a resonance voltage by a series resonance circuit of the winding 24 c and the capacitor 29 in the capacitor 29 to start the fluorescent lamp 22.

The operation of the second embodiment having the above configuration will be described. The DC output of DC power supply 21 is connected to inverter circuit 23
Is converted into AC by switching the FETs 25 and 26 alternately with the output signal of the oscillation circuit 28. The AC output is applied to a series resonance circuit of the winding 24c and the capacitor 29, and generates a voltage at both ends of the capacitor 29 sufficient to turn on the fluorescent lamp 22, and the fluorescent lamp 22 is turned on. After the fluorescent lamp 22 is turned on, the lamp current is limited by the winding 24c, and the fluorescent lamp 22 maintains the lighting.

The windings 24a and 24b, which are preheating circuits,
Outputs an AC having substantially the same phase as that of the winding 24c, and supplies the heating current to the two filaments 22a and 22b with the output. The polarity of the voltage generated from the windings 24a and 24b can be generated with the same polarity as in the first embodiment. Therefore, the current flowing through the windings 24a and 24b is only the heating current for the filaments 22a and 22b, and the same effect as in the first embodiment can be obtained.

In the second embodiment, if the driving frequency of the oscillation circuit 28 can be changed as the power changing means, the FETs 25 and 26 which are alternately switched are provided.
Can be varied, and the frequency of the alternating current output from the inverter 23 can be changed. Since the impedance of the winding 24c changes by changing the frequency, the power supplied to the fluorescent lamp 22 changes.
Thus, even if the lamp power is changed, the windings 24a,
The phase relationship between the output voltage of 24b and the lamp current is unchanged, and the lamp current does not always flow through the windings 24a and 24b. Therefore, the present invention, in which the discharge spot can be always concentrated on one point,
Lighting could be maintained stably.

In the above embodiment, a fluorescent lamp is shown as an example of a discharge lamp, but another discharge lamp having at least a filament may be used.

In the above embodiment, the lamp voltage or the lamp current is applied to one winding of the transformer, and the preheating circuit is constituted by the other two windings. The discharge lamp lighting inverter circuit and the preheating circuit inverter may be operated in synchronization with each other.When the inverter side terminal of the discharge lamp filament is used as a reference, the filament voltage and the lamp voltage are in opposite phases. Any configuration may be used.

Although the output frequency of the inverter circuit can be varied in the second embodiment as the power varying means, the power of the discharge lamp can also be varied by varying the output voltage of the DC power supplies 1 and 21. The power of the discharge lamp can also be changed by changing the value of the limiting element (capacitor 4, winding 24c) of the lamp current.

[0028]

As described above, according to the present invention, when the filament side of the discharge lamp is referenced to the inverter side terminal, the filament voltage and the lamp voltage are substantially reversed in phase.
The lamp current supplied to the discharge lamp can be directly supplied without passing through the preheating circuit, so that the loss can be reduced. In addition, since the discharge spot can be made one point, the discharge spot temperature does not decrease and the discharge lamp goes out. An effective effect that the lighting can be stably performed without any problem is obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a discharge lamp lighting device according to a first embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing the relationship between the polarity of a lamp voltage / lamp current and the polarity of a voltage generated in windings 11a and 11b.

FIG. 3 is a configuration diagram of a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional discharge lamp lighting device.

[Explanation of symbols]

 1,21 DC power supply 2,22 Fluorescent lamp 3,23 Inverter circuit 11a, 11b, 24a, 24b Preheating circuit

Continued on the front page (72) Inventor Masataka Ozawa 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Tetsuya Tahara 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Showa 61-1789 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 41/24

Claims (4)

(57) [Claims] 1. A a discharge lamp having a full Iramento, before
An inverter circuit for lighting a serial discharge lamp, having at least a preheating circuit for supplying heating current to the filament, when referenced to the inverter circuit side end <br/> terminal of said filament, said filament A discharge lamp lighting device, wherein the voltage of the discharge lamp and the voltage of the discharge lamp are substantially in opposite phases. Wherein said inverter circuit comprises a transformer on the output side, the one winding A of transformer secondary outputs substantially in phase exchange with the lamp voltage of the discharge lamp, before Symbol windings A 2. The discharge lamp lighting device according to claim 1, wherein at least one secondary winding B other than the above constitutes the preheating circuit. 3. The inverter circuit according to claim 1, further comprising : an oscillation circuit.
An FET driven by an output signal of the oscillation circuit.
In addition, a transformer is provided between the inverter circuit and the filament.
A primary winding of the transformer.
Current on the secondary side of the transformer
The discharge according to claim 1, wherein the discharge constitutes a thermal circuit.
Lamp lighting device. 4. The oscillation circuit is capable of controlling its own driving frequency.
4. The discharge lamp according to claim 3, wherein the discharge lamp is variable.
Lighting device.