JPH0963317A - Electrodeless lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To require no frequency varying means for a power resonator, and to make a device small and low-cost by using a small and low-cost variable condenser as the frequency varying means of a high-frequency oscillator. SOLUTION: In a circuit composed of a high-frequency oscillator 1, a power amplifier 3, a power resonator 4, an exciting coil 5, an electrodeless lamp 6, and the like, the output of the amplifier 3 is applied to the resonator 4 so as to put a resonance condenser 7 and the coil 5 in a resonance state, causing a high-frequency magnetic field to be generated. By providing a variable condenser 2 as a frequency varying means in the oscillator 1 and varying an oscillation frequency, the resonance of the resonator 4 can be properly selected so that the lighting can be conducted. Since respective impedance values can be varied by varying the frequency, even if the value of the condenser 7 and the value of the coil 5 are not varied, impedance matching is conducted so as to perform a drive with excellent efficiency. Thereby, as no frequency varying means is required for the resonator 4 and the small and low-cost variable condenser 2 is used, a small and low-cost device can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeless lamp lighting device for lighting a lamp by generating a high frequency electromagnetic field in a coil near a bulb.

[0002]

2. Description of the Related Art An electrodeless lamp has been developed in recent years, because it has no electrode inside the bulb and therefore has a large degree of freedom in the shape of the bulb and has a long life. As described in JP-A-3-138897, the conventional electrodeless lamp lighting device uses resonance frequency varying means such as an air variable condenser on the power resonator side, and the high frequency oscillator does not have frequency varying means. .

FIG. 5 shows a high-frequency oscillator 1 according to a conventional tuning method.
The high frequency power of the fixed frequency defined by is output from 3,
The electrodeless bulb 6 is turned on by inputting it to the excitation coil 5 via a resonance capacitor 7 such as an air variable condenser, and by the high frequency magnetic field generated thereby.

[0004]

In the above-mentioned conventional electrodeless lamp lighting device, since the power resonator is provided with the frequency varying means, a high withstand voltage and large resonant frequency varying means such as an air variable condenser is required. .

An object of the present invention is to provide an electrodeless lamp lighting device which does not require frequency varying means in the power resonator.

[0006]

The above object can be achieved by providing a high frequency oscillator with frequency changing means.

[0007]

In the present invention, since the oscillating frequency varying means is not required to have a high breakdown voltage and a large shape, it is possible to apply a low voltage, small and inexpensive variable capacitor or a variable inductance. Therefore, a small and inexpensive electrodeless lamp lighting device can be realized.

[0008]

1 is a block diagram of an embodiment of the present invention. 1 is a high frequency oscillator, 2 is a small and inexpensive variable capacitor, 3 is a power amplifier, 4 is a power resonator, 5 is an excitation coil, and 6 is an electrodeless lamp. The driving of the electrodeless lamp will be described with reference to FIG. The electrodeless lamp 6 can be turned on by applying a high frequency magnetic field to the electrodeless lamp 6. Here, the high frequency refers to a region of several MHz.

The high-frequency magnetic field can be generated by passing a high-frequency current through the excitation coil 5, and for that purpose it is necessary to apply a high voltage across the excitation coil 5. this is,
This can be achieved by applying the output of the power amplifier 3 to the power resonator 4 and bringing the resonance capacitor 7 and the excitation coil 5 into a resonance state. Since the maximum value of the output voltage from the power amplifier 3 is at most about the power supply voltage of the power amplifier 3,
When the commercial power source is rectified, it is about 140V, and when a general-purpose DC power source is used, it is often 24V or 48V. On the other hand, in order to maintain the lighting of the electrodeless lamp, a high frequency voltage of several hundred V is required across the excitation coil, and a larger voltage is required at the start of lighting. The power resonance circuit 4 amplifies this voltage, and the degree of increase of the voltage changes depending on the resonance quality Q of the resonator and the tuning degree.

FIG. 2 shows the characteristics of the resonator. When Q is good, a higher voltage can be obtained, but the oscillation frequency fo
Although it has a characteristic that the drop is large when it is out of the range, Q is determined by the resonance capacitor 7, the internal resistance component of the excitation coil 5, the reactance component, and the plasma impedance of the electrodeless lamp 6, so that the control of Q from outside Have difficulty. On the other hand, when the resonance characteristic is determined as shown in FIG. 2, the tuning degree can be changed by moving the frequency on the oscillation side to fo, f1 and f2, and thereby the output voltage can be controlled. The frequency on the oscillation side can be changed by providing the high frequency oscillator 1 with the frequency changing means 2.

With the above structure, the frequency varying means is provided on the high frequency oscillator side, and the tuning of the power resonator 4 can be appropriately selected by changing the oscillation frequency, thereby enabling lighting. Further, even if the value of the resonance capacitor 7 and the value of the excitation inductance 5 are not changed, if the frequency f is changed, the respective impedances (the resonance capacitor is 1 / (2πfC),
Since the excitation inductance can be changed by 2πfL, impedance matching becomes possible and efficient driving becomes possible.

FIG. 3 shows an embodiment of the circuit according to the present invention. In the power amplifier, a switching element 8 such as an FET capable of controlling high frequency power is constructed as a class D amplifier, and a crystal oscillation circuit 9 is used for driving the same. The frequency is made variable by connecting the variable capacitor 2 in series to the oscillator 13.
The variable capacitor 2 may be of a small size and low voltage.

FIG. 4 shows another embodiment in which a high-frequency oscillator circuit has an L
The C oscillator circuit 10 is used. Reference numeral 11 is a buffer circuit for driving the FET gate. In this case, the variable frequency means may be the variable capacitor 2 or the inductance 12 may be variable. All of them can be configured with a small and low voltage type.

[0014]

According to the present invention, since it is possible to tune on the small signal side, it is possible to use a low-voltage, small-sized and inexpensive component for the variable capacitor, so that the electrodeless lamp lighting device can be made small and inexpensive.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a characteristic diagram of a resonator.

FIG. 3 is a circuit diagram of a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a third embodiment of the present invention.

FIG. 5 is a block diagram of a conventional example.

[Explanation of symbols]

1 ... High-frequency oscillator, 2 ... Varicon, 3 ... Power amplifier, 4
… Power tuner, 5… Excitation coil, 6… Electrodeless valve, 7
… Resonant capacitors.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Ichikawa 888 Fujibashi, Ome City, Tokyo Hitachi Ltd. Heater Lighting Division

Claims (3)

[Claims] 1. An electrodeless lamp comprising a high-frequency oscillator, a high-frequency amplifier, a power resonator, and a discharge bulb filled with mercury or amalgam and an inert gas, wherein the oscillation frequency of the high-frequency oscillator is variable. And electrodeless lamp. 2. The electrodeless lamp according to claim 1, wherein the oscillation frequency of the high-frequency oscillator is determined by a crystal oscillation circuit and is variable by a variable capacitor connected in series with an oscillator. 3. The electrodeless lamp according to claim 1, wherein the oscillating frequency of the high frequency oscillator is determined by an LC oscillating circuit and is variable by adjusting electrostatic capacitance or inductance.