JPH0745383A - Electrodeless discharge lamp lighting unit - Google Patents

Abstract

PURPOSE:To reduce higher harmonic current components transmitted to the side of an exciting coil without increasing circuit loss and make a high frequency generation source hard to cause ringing. CONSTITUTION:Since the series circuit composed of a coil L1 and a capacitor CS is capacitive with the basic frequency omega0 of a high-frequency current outputted from FETs 1 and 2, it transmits the high-frequency current to the side of an exciting coil 3 without loss, whereby the lighting efficiency of an electrodeless lamp can be improved. Moreover, the synthesized impedance of the said series circuit becomes inductive to the third higher harmonic current or over of the said high frequency current, so the fifth higher harmonic waves or over become hard to be transmitted to the side of the exciting coil 3, therefore the radiation noise caused by the fifth or over higher harmonic components radiated from the said exciting coil 3 can be reduced, and the adverse effect on other equipment by this radiative noise can be lessened. Moreover, since the said synthesized impedance becomes inductive to higher harmonic components, the occurrence of ringing at FETs 1 and 2 can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeless discharge lamp lighting device, and more particularly to a matching circuit for connecting an excitation coil for supplying electromagnetic energy to an electrodeless discharge lamp and a high frequency generator.

[0002]

2. Description of the Related Art A conventional electrodeless discharge lamp lighting device supplies a high frequency current generated by switching of FETs 1 and 2 to an excitation coil 3 through a matching circuit composed of a capacitor CS and a capacitor CP, as shown in FIG.
It has a configuration in which electromagnetic energy generated in the excitation coil 3 is supplied to the electrodeless lamp 4 to light the electrodeless lamp. By the way, in the matching circuit shown in FIG.
Since the harmonic component of the high frequency current generated by the switching of the FETs 1 and 2 easily passes through the capacitor CS and is easily transmitted to the excitation coil 3, the electromagnetic radiation noise caused by the harmonic component is generated from the excitation coil 3. Increasing
This radiation noise has a drawback that it adversely affects other equipment (communication equipment, etc.). In addition, the small inductance existing in the high-frequency generation circuit composed of the FETs 1 and 2 and the capacitors CS and CP forming the matching circuit.
Cause resonance, and ringing easily occurs in the high frequency current generated by the FETs 1 and 2. For this reason, this ringing has a drawback that the harmonic component of the high-frequency current is further increased and the noise radiated from the excitation coil 3 is further increased, and the high voltage may be applied to the FETs 1 and 2 due to the ringing. However, when this high voltage exceeds the breakdown voltage of the FETs 1 and 2, there is a drawback that the FETs 1 and 2 are destroyed.

Therefore, in order to avoid the above-mentioned drawbacks, the matching circuit shown in FIG. 6 has been developed. In this matching circuit, capacitors CS and C
The coil L is inserted between P and the series impedance of the series circuit including the capacitor CS and the coil L is set to be inductive at the operating frequency. By doing so, the harmonic component of the high-frequency current generated from the FETs 1 and 2 is attenuated by the series circuit of the capacitor CS and the coil L, so that it is difficult to transmit to the excitation coil 3, and the harmonic component causes The radiated noise can be reduced to reduce adverse effects on other equipment. Further, since the combined impedance of the series circuit of the capacitor CS and the coil L is inductive, the slight inductance existing in the high frequency generation circuit composed of the FETs 1 and 2 and the matching circuit are less likely to cause resonance. As a result, ringing is less likely to occur when the FETs 1 and 2 are switched, and the FE
It is possible to prevent destruction of T1 and T2 and increase of harmonic components. However, in this circuit, in order to obtain the required matching condition, a large value of inductance is required and the reactive power of the circuit increases. On the other hand, since the Q of the coil obtained by the ordinary technique is not so large, there is a drawback that the circuit loss increases and the efficiency of lighting the electrodeless lamp 4 deteriorates.

[0004]

Since the matching circuit for connecting the high-frequency generation source and the excitation coil of the conventional electrodeless discharge lamp lighting device is composed of only capacitors,
The harmonic components of the high-frequency current generated by the high-frequency generator easily pass through the matching circuit and are easily transmitted to the excitation coil, and a large amount of radiation noise due to the harmonic components is emitted from the excitation coil to other appliances. It had the drawback of having an adverse effect. Further, a slight inductance existing in the harmonic generation source causes a matching circuit to resonate, which easily causes ringing during the switching operation of the FET constituting the harmonic generation source, and further increases the harmonic component. However, there is a drawback that the FET is damaged in some cases. Therefore, a circuit has been developed in which a coil is inserted in a matching circuit to prevent the harmonic components of the high frequency current output from the harmonic generation source from being easily transmitted to the excitation coil, and the radiation noise is reduced and the high frequency generation source is reduced. However, the Q of the coil cannot be increased, so that the reactive power increases and the circuit loss increases.

Therefore, the present invention eliminates the above-mentioned disadvantages, can reduce the harmonic current component transmitted to the excitation coil side without increasing the circuit loss, and can prevent ringing from occurring in the high frequency source. An object is to provide an electrode discharge lamp lighting device.

[0006]

SUMMARY OF THE INVENTION An electrodeless discharge lamp lighting device of the present invention is a high frequency source for generating a high frequency current, an electrodeless discharge lamp, and electromagnetic energy is supplied to the electrodeless discharge lamp to light it. An exciting coil, a first capacitor connected in parallel to the exciting coil to compensate for a reactive current flowing in the exciting coil, and a first capacitor inserted in a path for transmitting a high frequency current output from the high frequency source to the exciting coil. A series circuit including a coil and a second capacitor, the series circuit being capacitive with respect to a fundamental frequency component of the high frequency current, and having a higher harmonic component of the high frequency current. In contrast, it has a configuration that is inductive.

[0007]

In the electrodeless discharge lamp lighting device of the present invention, since the series circuit including the coil and the second capacitor is capacitive with respect to the fundamental frequency of the high frequency current output from the high frequency current generation source, The high-frequency current is transmitted to the excitation coil side without loss in this series circuit, and the electrodeless discharge lamp can be efficiently turned on. However, since the series circuit is inductive with respect to the higher order harmonic components of the high frequency current, the higher order harmonic components are attenuated in the series circuit and transmitted to the exciting coil side. It is possible to reduce the level of radiated noise caused by the higher-order harmonic components generated from, and eliminate the adverse effect of this noise on other devices. Further, since the series circuit is inductive to the higher harmonic components, it is possible to suppress the occurrence of ringing in the high frequency generation source.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the electrodeless discharge lamp lighting device of the present invention. Reference numerals 1 and 2 are FETs that constitute a high-frequency generation source, and generate high-frequency current by switching with a drive circuit (not shown). 3 is an electrodeless lamp 4
An excitation coil for supplying electromagnetic energy to the electrode 4, an electrodeless lamp that is lit by the electromagnetic energy supplied from the excitation coil 3, CS and CP are capacitors that form a matching circuit, L1 is a coil that forms a matching circuit, and a capacitor The CP, CS, and coil L1 constitute the matching circuit of this example.

Next, the operation of this embodiment will be described. F
The high frequency current generated by the switching of ET1 and ET2 is supplied to the excitation coil 3 via the matching circuit including the capacitors CS and CP and the coil L1. Thereby, the electromagnetic energy generated in the excitation coil 3 is supplied to the electrodeless lamp 4 and the electrodeless lamp 4 is turned on.
The capacitor CP compensates the reactive current of the excitation coil 3 and performs an impedance conversion action in cooperation with CP and LI.

By the way, the series circuit of the capacitor CS and the coil L1 forming the matching circuit is designed as follows, and the synthetic impedance of the series circuit of the coil L1 and the capacitor CS is the switching operating frequency of the FETs 1 and 2 ( Ω ₀ is the same as the fundamental frequency of the generated high-frequency current, and is capacitive, and inductive to higher harmonic components. The coil L
1, capacitor CS, capacitor CP and excitation coil 3
It is assumed that the series resonance frequency of the load side circuit created by, for example, is set to the frequency of the substantially fundamental wave of the high frequency current, for example, the frequency of the 2.5th order. Here, the reactance of the coil L1 is X _L1 and the reactance of the capacitor CS is X _CS
And the operating frequency of the FETs ₁ and 2 is ω ₀ , the following relationship must be established in order to make the combined impedance capacitive at the operating frequency. That is, X _L1 = ω ₀ L1, X _CS = 1 / (ω ₀ CS), and when the relationship of ω ₀ L1- {1 / (ω ₀ CS)} <0, the combined impedance becomes capacitive. Become. Therefore, ω ₀ L1 <{1 / (ω ₀ CS)} CS <{1 /
(Ω ₀ ² L1)} (1) Therefore, the inductance of the coil L1 and the capacitance of the capacitor CS are set so as to satisfy the relationship of the expression (1). Moreover, in this example, the series resonance frequency of the matching circuit including the load circuit made up of the coil L1, the capacitors CS and CP, the excitation coil 3 and the like is set to the equation (1) so that the series resonance frequency becomes the 2.5th order of the high frequency current. The values of the coil L, the capacitors CS and CP, and the excitation coil 3 are determined while maintaining the relationship of. Therefore, the composite impedance of the load circuit is inductive with respect to harmonic currents of the order of 2.5 and above of the high frequency current.

FIG. 2 is a graph in which the magnitude of the high frequency current flowing through the excitation coil 3 is plotted for each harmonic of this high frequency current. B shows the characteristics of this example shown in FIG. 1, and B shows the characteristics of the conventional example shown in FIG. However,
The harmonic order 1 on the horizontal axis is the operating frequency ω ₀ of the FETs 1 and ₂ , and the series resonance frequency of the circuit when the excitation coil 3 side is viewed from the output side of the FETs 1 and 2 in FIG. It is assumed that the frequency is set to the high frequency ω of the 2.5th order of the current. As a result, the characteristic of the current flowing through the excitation coil 3 shown in FIG. 1 is higher than the conventional characteristic b up to the first to third order harmonics, but the harmonic order becomes higher than the third order. Accordingly, the harmonic current value flowing through the excitation coil 3 becomes smaller than that of the conventional characteristic B. Here, the radiated noise caused by the harmonic current flowing through the excitation coil 3 is the radiated noise frequency range due to the first to third harmonic components is the frequency range assigned to the lighting circuit that drives the electrodeless lamp or the like. Therefore, even if the radiation noise caused by the first to third harmonic components is emitted from the excitation coil 3, it hardly affects other appliances. However, since the radiated noise due to the fifth and higher harmonic components comes to the frequency range of television broadcasting, the radiated noise due to the fifth and higher harmonic components causes interference noise to broadcasting equipment and communication equipment. It will have an adverse effect. Therefore, the present example is designed to reduce the magnitude of the radiation noise caused by the higher-order harmonic components as compared with the conventional example.

According to the present embodiment, the coil L1 is inserted in the matching circuit, and the coil L1 is applied to the third and higher harmonic currents of the high frequency current output from the FETs 1 and 2.
Since the combined impedance of the series circuit including the capacitor and the capacitor CS is designed to be inductive,
The rate at which higher-order harmonic currents and higher harmonics are transmitted to the excitation coil 3 can be reduced by the series circuit, and the level of radiation noise due to the fifth-order and higher harmonic components generated from the excitation coil 3 can be reduced. Thus, it is possible to eliminate the adverse effect of this noise on other devices. Moreover, since the combined impedance of the series circuit composed of the coil L1 and the capacitor CS is capacitive at the switching operation frequency ω ₀ of the FETs _{1 and 2} , the reactive power consumed in this circuit does not increase and the circuit loss is reduced as shown in FIG. It can be reduced to about 1/10 of that of the conventional matching circuit shown in FIG.
Further, since the series circuit is inductive to the harmonic currents of the third order or higher, it is possible to suppress the occurrence of ringing during the switching operation of the FETs 1 and 2, and the harmonics caused by this ringing can be suppressed. While eliminating the increase of the component, F
It is possible to prevent destruction of ET1 and ET2.

FIG. 3 is a circuit diagram showing another embodiment of the present invention. In this example, a transformer T is used for the matching circuit and F
It is possible to increase the degree of freedom in designing the high-frequency generation source including the ETs 1 and 2, or increase the stability of the load side circuit including the matching circuit. Here, the capacitor C of this example is for DC cutting, and the capacitance of the capacitor C is much larger than that of the capacitor CS. Therefore, if the leakage inductance of the transformer T is L1, the equalization circuit of this example is as shown in FIG. As shown, the circuit is equivalent to a circuit in which the transformer T has an elevating function. This is equivalent to the matching circuit of the above embodiment, and similar operation and effect can be obtained.

[0014]

As described above, according to the electrodeless discharge lamp lighting device of the present invention, the harmonic current component transmitted to the excitation coil side can be reduced and the ringing at the high frequency generation source can be performed without increasing the circuit loss. Can be less likely to occur.

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram obtained by plotting the magnitude of a high frequency current flowing in the excitation coil shown in FIG. 1 for each harmonic of the high frequency current.

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

4 is an equalization circuit diagram of the circuit of FIG.

FIG. 5 is a circuit diagram showing an example of a conventional electrodeless discharge lamp lighting device.

FIG. 6 is a circuit diagram showing another example of a conventional electrodeless discharge lamp lighting device.

[Explanation of symbols]

1, 2 ... FET 3 ... Excitation coil 4 ... Electrodeless lamp CS, CP ... Capacitor L1 ... Coil

Claims (4)

[Claims] 1. A high frequency source for generating a high frequency current,
An electrodeless discharge lamp, an excitation coil for supplying electromagnetic energy to the electrodeless discharge lamp to turn on the electrodeless discharge lamp, a first capacitor connected in parallel with the excitation coil to compensate a reactive current flowing in the excitation coil, and A series circuit including a coil and a second capacitor inserted in a path for transmitting a high frequency current output from a high frequency source to the excitation coil, the series circuit including a fundamental frequency component of the high frequency current. An electrodeless discharge lamp lighting device, which is capacitive with respect to the above, and inductive to higher harmonic components of the high frequency current. 2. The electrodeless discharge lamp lighting device according to claim 1, wherein the high frequency current generation source is a voltage type inverter circuit. 3. The high-order series resonance frequency of the circuit seen from the output side of the high-frequency generation source as viewed from the excitation coil side is not an integral multiple of the fundamental frequency of the high-frequency current. The electrodeless discharge lamp lighting device described. 4. The high-order series resonance frequency of the circuit viewed from the output side of the high-frequency generation source as seen from the excitation coil side is near 2.5 times or 3.5 times the fundamental frequency of the high-frequency current,
4. The electrodeless discharge lamp lighting device according to claim 3, wherein it is set to any one of about 4.5 times.