JPH0613191A - Electrodeless discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To prevent a counterflow of a high frequency electric current to a direct current electric power supply part. CONSTITUTION:An electrodeless discharge lamp lighting device has a direct current electric power supply part 2, an inverter part 3 to convert direct current electric power supply from this direct current electric power supply part 2 into high frequency electric power supply, an electrodeless discharge lamp 14 formed by sealing up at least dischargeable gas or vapor in a lamp tube 14a and a lighting coil 7 which is arranged in the vicinity of the lamp tube 14 and to which high frequency electric power is supplied from the inverter part 3. In a lighting device to light the electrodeless discharge lamp 14 by inputting the high frequency electric power to this lamp tube 14a through a plasma ring in the lamp tube 14a being coupled magnetically with this lighting coil 7, the direct current electric power supply part 2 and at least a final stage circuit 5 of the inverter part 3 are connected to each other through an inductor contained low-pass filter 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeless discharge for lighting a lamp by supplying high frequency power from a lighting coil wound around the electrodeless discharge lamp to a plasma ring in the lamp which is magnetically coupled. The present invention relates to a lamp lighting device, and more particularly, to an electrodeless discharge lamp lighting device improved so as to prevent backflow of a high frequency current to a DC power supply unit.

[0002]

2. Description of the Related Art In an electrodeless discharge lamp, a lamp body (outer tube) made of quartz glass is formed in a spherical shape, and for example, krypton gas or a luminescent metal that vaporizes when excited is enclosed in the lamp body. In this electrodeless discharge lamp, a lighting coil is wound around the lamp body for several turns (about 1 to 3 turns), and a high frequency current of a short wave band of several MHz or more is passed through the lighting coil. The discharge gas or vapor in the lamp body is excited to form a plasma ring that is magnetically coupled to the coil.
As a result, high-frequency power is supplied from the lighting coil to the plasma ring in the lamp body that is magnetically coupled, and the electrodeless discharge lamp is lit at high frequency. Such an electrodeless discharge lamp has excellent characteristics such as high efficiency, high brightness, high color rendering, and long life.

4 and 5 show the structure of a lighting device for lighting the electrodeless discharge lamp. In these figures, the commercial AC power supply 1 is converted into a DC power supply by being rectified and smoothed by the DC power supply unit 2, and then converted into a high frequency power supply of, for example, 13.56 MHz with high efficiency by the inverter unit 3. The inverter unit 3 includes a drive circuit 4 and a switching element 5 driven by the drive circuit 4.
and a half-bridge type final stage circuit 5 composed of a and 5b. The drive circuit 4 is supplied with an oscillation output from an oscillation circuit 16 to which a crystal oscillator 15 is connected. A lighting coil 7 is connected between the output terminals of the inverter unit 3 via a variable capacitor 6, and a capacitor 8 is connected in parallel to the lighting coil 7 constituting the main circuit. The lighting coil 7 is wound around the lamp for several turns. Here, the capacitors 6 and 8 form a resonance circuit with the lighting coil 7, and also form a matching circuit 17 for impedance correction for matching the high frequency power supply and the lamp load. Further, the lighting coil 7 is connected in parallel with a starting circuit 13 including a capacitor 9, a parallel resonance circuit portion of the starting coil 10 and the capacitor 11, and a series circuit of a starting switch 12. The high voltage generation point, which is the connection point between the capacitor 9 and the parallel resonant circuit, is the lamp 1
4 gas probe 14b. Here, the capacitors 9 and 11 are used for tuning, and by changing the degree of resonance of the starting circuit 13 by the capacitors 9 and 11, the distribution of power to the main circuit and the starting circuit 13 is changed, or the starting circuit is operating. It has a function of matching the combined impedance of the main circuit and the starting circuit 13 in the high frequency power supply. The electrodeless discharge lamp 14 is
For example, krypton gas (Kr), which is a discharge gas, is sealed in the main tube 14a, which is an arc tube, at about 250 torr, and NaI,
CeI etc. are enclosed. This main tube 14
From the top of a, a gas probe 14b forming a starting energy injection pipe section separated from the main tube 14a by a partition wall.
Is extended. Krypton gas is enclosed in the probe 14b at about 10 torr.

In the electrodeless discharge lamp lighting device configured as described above, when the switch 12 is turned on at the time of starting to supply high frequency power from the inverter unit 3 to the main circuit and the starting circuit 13, the high voltage generated in the starting circuit 13 is generated. Is a gas probe 1
4b is applied. As a result, the gas in the gas probe 14b is discharged and destroyed, and the gas in the main tube 14a is brought into a glow discharge state.
A plasma ring is formed in a. When the formation of this plasma ring is detected by a detection circuit (not shown),
Upon receiving this detection signal, the starting switch 12 is turned off. After that, lighting power is supplied from the lighting coil 7 to the magnetically coupled plasma ring, and the lamp 14 is lit at high frequency.

[0005]

By the way, in such an electrodeless discharge lamp lighting device, looking at the state before the lamp 14 is lit, the lighting coil 7 not yet coupled to the plasma ring, the matching circuit 17 and the starting circuit. The circuit 13 serves as a load on the final stage circuit 5. The resonance circuit configured by the lighting coil 7 and the matching circuit 17 has a high Q value (sharpness) of about 300 to 500 in order to suppress the loss during lamp lighting as much as possible. In addition, in order to start the discharge of the lamp 14, the lighting coil 7
Since a strong magnetic field has to be formed at, the load of the final stage circuit 5 has an extremely low impedance. Under such conditions, high-frequency current is likely to sneak into the DC power supply unit 2. Therefore, conventionally, in order to solve such a problem, the bypass capacitor 18 is connected between the DC power input terminal of the final stage circuit 5 and the ground. However, no matter how much the capacity of the bypass capacitor 18 is increased, the equivalent series resistance (ES
Even if R) was lowered, it was extremely difficult to prevent the high-frequency current from flowing back to the DC power supply unit 2. This is the bypass capacitor 18, but there is a parasitic inductance component.
Moreover, the value is almost the same as the load resistance at the time of starting. Such a reverse flow of the high frequency current hinders the normal operation of the DC power supply unit 2 and causes problems such as the DC power supply unit 2 operating intermittently and the output current decreasing.

The present invention has been proposed in order to solve the problems of the prior art as described above, and provides an electrodeless discharge lamp lighting device capable of preventing a high-frequency current from flowing back to a DC power supply section. With the goal.

[0007]

In order to achieve this object, the present invention provides a DC power source section, an inverter section for converting the DC power source from the DC power source section into a high frequency power source, and at least a discharge characteristic in the lamp tube. An electrodeless discharge lamp filled with gas or vapor and a lighting coil arranged near the lamp tube and supplied with high-frequency power from the inverter section, and a lamp magnetically coupled to the lighting coil. In a lighting device for lighting an electrodeless discharge lamp by inputting high-frequency power into the lamp tube via a plasma ring in the tube, the DC power supply section and at least the final stage circuit of the inverter section include an inductor. It is configured to be connected via a low-pass filter.

[0008]

According to the above construction, since the DC power supply unit and at least the final-stage circuit of the inverter unit are connected via the low-pass filter including the inductor, the inverter unit should backflow to the DC power supply unit. The high-frequency current to be blocked is blocked by this low-pass filter.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the electrodeless discharge lamp lighting device according to the present invention will be described in detail below with reference to the drawings. In the description, the same parts as those in the conventional example are designated by the same reference numerals, and the description of the overlapping parts will be partially omitted. An embodiment of this electrodeless discharge lamp lighting device is shown in the block diagram of FIG. In this figure, the DC power supply unit 2 converts the commercial AC power supply 1 into a DC power supply and supplies the DC power supply 2 to the final stage circuit 5 of the inverter unit 3. In the inverter unit 3, the input DC power source is converted into a high frequency power source, and the matching circuit 1
7 (see FIG. 5) to the lighting coil 7 of the electrodeless discharge lamp 14. A low-pass filter (low-pass filter) including an inductor is provided between the DC power supply unit 2 corresponding to the terminals 20 and 21 in FIG. 4 and the final stage circuit 5 of the inverter unit 3.
It is connected via 22. This low pass filter 22
It is configured as follows. Ferrite beads 23, 23 are individually connected to the power output terminal 20a and the ground terminal 20b of the DC power supply unit 2, respectively.
4b is connected. These connection wires 24a and 24b are twisted with each other to form a twisted cable 25. At the terminal end of the twisted cable 25, the ferrite beads 23 are fitted together into the two connection wires 24a and 24b. Further, a ferrite bead 23 is fitted into the connection 24a on the power supply side where the twisted cable 25 is unwound, and then connected to the power supply input terminal 21a of the final stage circuit 5. Further, after the ferrite beads 23 are fitted into the other grounding side connection 24b, the final stage circuit 5
Is connected to the ground side terminal 21b. Also, the terminal 21
A capacitor 26 is connected between a and 21b. Here, as shown in FIG. 2, each ferrite bead 23 made of a ferromagnetic material has a columnar shape with a cable insertion hole 23a bored in its axis, and has a length L of about 30 mm.
The magnetic permeability μ is about μ = 850. Low-pass filter 2
In 2, each ferrite bead 23 acts as an inductor. Such a low-pass filter 22 is installed in the DC power supply unit 2
Since it is provided between the end circuit 5 and the final stage circuit 5, the high-frequency current can be prevented from flowing back to the DC power supply unit 2.

Next, an example of another low-pass filter 27 connected between the DC power supply unit 2 and the final stage circuit 5 will be described with reference to FIG. In the low-pass filter 27, the connection wires 24a and 24b connected to the power-source-side output terminal 20a and the ground-side terminal 20b of the DC power supply unit 2 are twisted into a twisted cable 25. Inductors 28 and 29 are connected in series to the connection lines 24a and 24b at the end portions, respectively. These inductors 28 and 29 are in-phase transformers. The other end of the inductor 28 is connected to the power supply input terminal 21a of the final stage circuit 5 via the inductor 31, and the other end of the inductor 29 is connected to the ground side terminal 21b of the final stage circuit 5 via the inductor 32. There is.
These inductors 31 and 32 are composed of toroidal cores. Further, between the connection point of the inductors 28 and 31 and the connection point of the inductors 29 and 32, 0.0
A capacitor 30 of about 1 μF is connected. By providing the low-pass filter 27 having such a configuration, it is possible to prevent the high-frequency current from flowing into the DC power supply unit 2.

A low-pass filter including an inductor may be connected between the DC power supply unit 2 and the drive circuit 4 and between the DC power supply unit 2 and the oscillation circuit 16.

[0012]

As described above, according to the present invention, since the DC power supply unit and the final stage of the inverter unit are connected via the low-pass filter including the inductor, the DC power supply unit for high frequency current is connected. Can be prevented from flowing back into the. As a result, it is possible to prevent problems such as intermittent operation of the DC power supply unit that have occurred in the past, ensure stable operation of the DC power supply unit, and prevent the output current of the inverter unit from decreasing. Good starting and lighting.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an electrodeless discharge lamp lighting device according to the present invention.

FIG. 2 is a perspective view showing a ferrite bead.

FIG. 3 is a block diagram showing an electrodeless discharge lamp lighting device of another embodiment.

FIG. 4 is a schematic overall configuration diagram of a general electrodeless discharge lamp lighting device.

FIG. 5 is a circuit diagram showing a general electrodeless discharge lamp lighting device.

[Explanation of symbols]

 1 Commercial AC power supply 2 DC power supply part 3 Inverter part 4 Drive circuit 5 Final stage circuit 7 Lighting coil 13 Starting circuit 14 Electrodeless discharge lamp 14a Main tube 16 Oscillation circuit 17 Matching circuit 20a Power supply side output terminal 21a Power supply input terminal 20b, 21b Grounding side terminal 22,27 Low-pass filter 23 Ferrite bead 24a, 24b Connection 25 Twist cable 26,30 Capacitor 28,29,31,32 Inductor

Claims (1)

[Claims] 1. A DC power supply unit, an inverter unit for converting a DC power supply from the DC power supply unit into a high frequency power supply, an electrodeless discharge lamp in which at least a discharge gas or vapor is sealed in a lamp tube, and a lamp tube. And a high-frequency power supply from the inverter section, and a high-frequency power is supplied to the lamp tube via a plasma ring in the lamp tube that is magnetically coupled to the lighting coil. In the lighting device for lighting the electrodeless discharge lamp by inputting to the above, the direct current power supply unit and at least the final stage circuit of the inverter unit are connected via a low-pass filter including an inductor. Electrodeless discharge lamp lighting device.