JP2001015283A - Lighting circuit for electrodeless field discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency (radio frequency) power supply device assuring good matching with an electrodeless field discharge lamp, a high conversion efficiency from DC power into a high-frequency power, simple in the circuit configuration, and capable of operating accurately even if the constant of component varies to a certain degree. SOLUTION: Matching with an electrodeless field discharge lamp is established by adjusting the number of turns in the secondary winding of a matching transformer, and transistors Q1 and Q2 are installed in the primary side circuit of the matching transformer and allowed to operate as a Class D operation oscillator circuit for current switching, and thereby the conversion efficiency from DC power into high-frequency (radio frequency) power is heightened. The drains of the transistors Q1 and Q2 are furnished with L1 and C1 and L2 and C2, respectively, and they are allowed to operate as a series resonance circuit, and feedback capacitors are installed between the drain of Q1 and the gate of Q2 and between the drain of Q2 and the gate of Q1. Each gate should be equipped with a starter circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting circuit for an excimer lamp using an electrodeless electric field discharge, a lighting circuit for a germicidal lamp using an electrodeless electric field discharge, a lighting circuit for a fluorescent lamp using an electrodeless electric field discharge, The present invention relates to a high-frequency (radio-frequency) power supply widely used for a lighting circuit of an electroded lamp that lights at a frequency, a power supply apparatus for plasma CVD, and the like.

[0002]

2. Description of the Related Art As a technique related to the lamp of the present invention, there is, for example, Japanese Patent Application Laid-Open No. 62-40196. Among them, as shown in FIG. 3 and FIG.
A circuit for lighting a fluorescent lamp by electrodeless electric field discharge using one T transistor Q1 is shown. In this circuit, as a method of generating a high voltage required at the time of starting a lamp, a series resonance circuit constituted by a capacitor C1 and an oscillation coil L1 shown in FIG.
The resonance voltage generated at both ends is used. 1 in the figure
Is an AC power supply, 2 is a high frequency power supply, 3 is a lamp bulb, and 4 is an external power supply.

[0003]

However, according to this method, the internal gas pressure is changed (for example, from 400 Pascal to 1300
(Change to Pascal) had the disadvantage of not being able to start. In addition, since the gate of the MOSFET transistor Q1 is always divided by the resistors R1 and R2 and a DC voltage is applied through the resistor R3, the operation is Class A. Therefore, DC power is converted to RF (radio frequency)
There is a drawback that the efficiency of converting to electric power is 50% or less, which is extremely inefficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is compatible with any electrodeless electric field discharge lamp, has a high conversion efficiency from DC power to high frequency (radio frequency) power, and has a high circuit efficiency. It is an object of the present invention to provide a high-frequency (radio frequency) power supply device which has a simple configuration and can operate accurately even if the number of components slightly fluctuates.

[0005]

Means for Solving the Problems The present invention has the following arrangement to solve the above-mentioned problems. That is, claim 1 relates to a lighting circuit of an electrodeless electric discharge lamp. Then, a voltage generated on the secondary side of the matching transformer is applied to an external electrode installed outside the lamp bulb filled with the discharge gas of the discharge medium by using a matching transformer.

According to the first aspect of the invention, by adjusting the number of turns on the secondary side of the matching transformer, an arbitrary electrodeless electric field discharge lamp can be turned on. Also, by adjusting the coupling coefficient between the primary side and the secondary side of the matching transformer, it is possible to cope with a lamp whose impedance changes drastically with the lapse of time after lighting. For lamps that discharge in a pulse in one cycle, matching
There is no problem because the resonance power stored in the parallel resonance circuit constituted by the oscillation coil L3, the capacitor C3, and the capacitor C4 on the primary side of the transformer corresponds.

According to a second aspect of the present invention, in the lighting circuit of the electrodeless electric discharge lamp according to the first aspect, a parallel resonance circuit composed of L3, C3, and C4 is provided on the primary side of the matching transformer. Connected to the primary side of the matching transformer from the drains of the transistors Q1 and Q2 through the capacitors C1 and C2.
2 is configured to operate as a current switching type class D operation.

According to the second aspect of the present invention, the transistor Q connected to the primary side of the matching transformer
By completely turning on and off 1 and Q2,
Circuit operation for eliminating power loss in the transistors Q1 and Q2 can be performed. That is, a class D operation of current switching is performed. In this case, when the transistor is ON, the drain voltage is zero, and when the transistor is OFF, the drain voltage is applied for a half cycle of the sine wave.

According to a third aspect of the present invention, in the lighting circuit of the electrodeless electric discharge lamp according to the second aspect, an oscillating coil L1, a capacitor C1, and an oscillating coil L2, a capacitor C2 are provided, and these are connected in series resonance. Operate as a circuit, and the drain of Q1 and the gate of Q2, and
Feedback capacitors C5 and C6 are connected between the drain of Q2 and the gate of Q1 to constitute a self-excited oscillation circuit.

According to the third aspect of the present invention, a signal for completely alternately turning on and off the transistors Q1 and Q2 is obtained from an external oscillator. That is, the drain voltages of the transistors Q1 and Q2 are set to 180
Utilizing the fact that the capacitors are deviated from each other, the capacitors C5 and C6 for feedback are connected from the drain to the gate, and self-oscillation is performed. Therefore, an external oscillator is not required, thereby simplifying the circuit and operating the external oscillator. There is an advantage that the electric power required for this is unnecessary. This state becomes more remarkable as the oscillation frequency increases. Another advantage is that the oscillation frequency can be automatically changed to cope with a change in the electrical impedance of the lamp.

According to a fourth aspect of the present invention, in the lighting circuit of the electrodeless electric discharge lamp according to the third aspect, Q1 and Q
A starting circuit for causing one or both of the two gates to perform an oscillating operation is provided.

According to the fourth aspect of the invention, since the transistors Q1 and Q2 use MOSFET transistors, unless the gate voltage is made positive, the drain current does not flow and oscillation cannot be performed. In order to oscillate, there is a method in which the gate voltage of one of the transistors Q1 and Q2 is temporarily made positive at the time of starting, and the oscillation is forcibly oscillated. This method is effective when the oscillation frequency is low (1 MHz or less). Because MOSF
This is because it is difficult to drive the capacitive load of the gate of the ET transistor at high speed.

As another starting method, a transistor Q
The gate voltage of both Q1 and Q2 is temporarily made positive, a slight drain current flows, and the noise component in the power supply voltage is selected by the parallel resonance circuit composed of L3, C3 and C4, and the expanded voltage Is amplified as an analog linear amplifier, and the operation is shifted to a switching operation.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to FIGS. 1 to 3 according to claims 1 to 4 according to the present invention. FIG. 1 shows an embodiment of the present invention, in which T1 is a matching transformer, Q1 and Q2 are MOSFET transistors, oscillation coils L1 and C1 and oscillation coils L2 and C2 are series resonance circuits, oscillation coils L3 and C3. , A capacitor C4 is a parallel resonance circuit, and 10 is a starting circuit for starting the oscillator of the present invention. FIG. 3 is a block diagram of the electrodeless electric field discharge lamp device according to the present invention. 1 is a DC power supply that converts AC power into DC power,
It is supplied to the oscillator 2. Reference numeral 3 denotes a rod-shaped lamp bulb, which is filled with a discharge gas. Reference numeral 4 denotes an external electrode attached to the outside of the lamp bulb, and a plasma can be generated inside the lamp bulb by applying a high frequency (radio frequency) high voltage to the external electrode tube.

The method of starting the oscillator according to the present invention includes a method of starting the MOSFET transistor by performing an analog linear operation and a method of starting the oscillator digitally.
There is a method of applying a positive pulse voltage to the gate voltage of the OSFET transistor. A digital method will be described.

Although it is possible to start from either Q1 or Q2, if starting from Q1, a positive pulse is applied to the gate of Q1 and a drain current flows through Q1. L
1 stores the energy of the magnetic field. When the pulse of the positive polarity disappears, the drain current stops flowing, and the energy of the magnetic field stored in L1 causes Q2 to decrease as shown in FIG.
1 is increased. This rise in the drain voltage causes the gate voltage of Q2 to rise by the feedback capacitor C5, and a drain current flows through Q2. Energy of the magnetic field is stored in L2. The voltage at the drain of Q1 is L
The voltage waveform for a half cycle of the sine wave is obtained by the series resonance circuit composed of 1 and C1.

When the voltage at the drain of Q1 decreases, the gate voltage of Q2 also decreases due to C5, the drain current of Q2 stops flowing, and the energy of the magnetic field stored in L2 causes the current of Q2 to decrease as shown in FIG. The drain voltage increases. This rise in the drain voltage causes the gate voltage of Q1 to rise by the feedback capacitor C6, and a drain current flows through Q1. The energy of the magnetic field is stored in L1. The voltage at the drain of Q2 has a voltage waveform corresponding to a half cycle of the sine wave by the series resonance circuit composed of L2 and C2. When the voltage at the drain of Q2 decreases, the gate voltage of Q1 also decreases due to C6, the drain current of Q1 stops flowing, and the energy of the magnetic field stored in L1 increases the drain voltage of Q1.

Thereafter, similarly, the drain voltages of Q1 and Q2 are oscillated, as shown in FIG. 2, as a half-cycle voltage waveform of a sine wave having a phase difference of 180 degrees from each other. This oscillation energy is supplied by C1 and C2 to a parallel resonance circuit composed of L3, C3 and C4, and a resonance current flows through the primary side of the matching transformer. Further, this energy is transferred to the load (ramp) on the secondary side of the matching transformer due to the change in magnetic flux in the matching transformer.

FIG. 1 shows an embodiment of the present invention. The lamp as a load is a coaxial cylindrical electrodeless E (electric field) discharge excimer lamp. The discharge vessel 20 was made of quartz glass having a total length of about 300 mm, and was formed into a hollow cylindrical shape by coaxially arranging an outer diameter of the outer tube of about 35 mm, a wall thickness of 1.5 mm, an outer diameter of the inner tube of about 11 mm, and a wall thickness of 1 mm. Things. An external electrode 2 is provided on the outer surface of the outer tube.
1 is installed. In addition, the discharge vessel is filled with a rare gas, xenon gas, at 20,000 Pascal, and when the oscillation frequency of the oscillation circuit is 2.5 MHz and the lamp input is 200 W,
The efficiency of converting DC power to RF (radio frequency) power is 80
% Or more.

In general, class D and class E amplifiers have a theoretical efficiency of converting direct current to high frequency of 100%. However, class E amplifiers have more waveform distortion than class D amplifiers and have electromagnetic interference (EMI). ) It is disadvantageous in measures. Class D amplifiers are classified into a voltage switching type and a current switching type. The voltage switching type has a drawback that it is difficult to generate a high-frequency voltage higher than a predetermined value. As a lighting circuit, a current switching type class D amplifier is superior.

Although the MOSFET transistor is not suitable for an analog linear operation, it is advantageous for a digital switching operation. In the oscillation circuit of the present invention, the oscillating operation cannot be performed only by applying the DC voltage, but once the oscillating operation occurs, the operation can be continued thereafter. Therefore, only when a DC voltage is applied to the oscillation circuit, a circuit for setting the gate voltage of the MOSFET transistor to be positive and starting the oscillation operation is required. In addition, since the source of the current switching type class D amplifier is fixed to the ground, the starting circuit is easier to design than the voltage switching type class D amplifier in which the source of one MOSFET transistor is floating. .

[0022]

According to the first to fourth aspects of the present invention, matching with an arbitrary electrodeless electric field discharge lamp is achieved, and the conversion efficiency from DC power to high frequency (radio frequency) power is high. There is a special effect that a high-frequency (radio frequency) power supply device that can operate accurately even if the circuit configuration is simple and the component constants slightly vary is provided.

[Brief description of the drawings]

FIG. 1 is a lighting circuit of an electrodeless electric discharge lamp according to the present invention.

FIG. 2 is an operation waveform diagram of a lighting circuit of the electrodeless electric discharge lamp according to the present invention.

FIG. 3 is a block diagram of a known electrodeless electric field discharge lamp device.

FIG. 4 is a lighting circuit of a conventional electrodeless electric discharge lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2 High frequency power supply (oscillator) 3 Lamp / bulb 4 External electrode 10 Starting circuit 20 Discharge vessel 21 External electrode

Claims (4)

[Claims] In a lighting circuit of an electrodeless electric field discharge lamp, a matching transformer is used, and a secondary side of the matching transformer is connected to an external electrode installed outside a lamp bulb filled with a discharge gas of a discharge medium. An electrodeless electric discharge lamp lighting circuit characterized by applying a voltage generated to the lamp. 2. A parallel resonance circuit comprising an oscillating coil L3, a capacitor C3, and a capacitor C4 is provided on the primary side of a matching transformer, and the primary of the matching transformer is passed from the drains of the transistors Q1, Q2 through the capacitors C1, C2. Side, and Q1, Q
2. The circuit for lighting an electrodeless electric discharge lamp according to claim 1, wherein said circuit 2 is operated as a current switching type class D operation. 3. An oscillation coil L1, a capacitor C1, and an oscillation coil L2, a capacitor C2 are provided in a parallel resonance circuit to operate them as a series resonance circuit, and a drain of the transistor Q1 and a gate of the transistor Q2 are provided.
3. A lighting circuit for an electrodeless electric discharge lamp according to claim 1, wherein feedback capacitors C5 and C6 are connected between the drain of Q2 and the gate of Q1 to form a self-excited oscillation circuit. 4. A non-electrode according to claim 1, wherein a starting circuit for causing one or both of the gates of the transistor Q1 and the transistor Q2 to perform an oscillating operation is provided. Electric discharge lamp lighting circuit.