JP3823709B2 - Power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply device used in an electrodeless discharge lamp lighting device that emits light by applying a high-frequency electromagnetic field to an electrodeless discharge lamp.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a power supply device that supplies an electric power to an electrodeless discharge lamp as a load, for example, there is one having a circuit configuration as shown in FIG.
The conventional power supply device shown in FIG. 5 is a transparent glass or a spherical glass bulb coated with a phosphor on its inner wall, in which a discharge gas (for example, mercury or a rare gas) such as inert gas or metal vapor is sealed. An electrode discharge lamp 1, an induction coil 2 disposed close to the spherical outer periphery of the electrodeless discharge lamp 1, a high-frequency power source 3 connected to the induction coil 2 and supplying high-frequency power to the induction coil 2, A matching circuit 4 is provided to match both the induction coil 2 and the high-frequency power source 3 to eliminate reflection and efficiently supply high-frequency power to the electrodeless discharge lamp 1.
[0003]
Then, a high frequency current of several hundred kHz to several hundred MHz is supplied from the high frequency power source 3 to the induction coil 2 to generate a high frequency magnetic field in the induction coil 2 to supply high frequency power to the electrodeless discharge lamp 1 and to perform electrodeless discharge. A high frequency plasma current is generated in the lamp 1 to generate ultraviolet rays or visible light.
The high frequency power supply 3 includes a drive circuit 9 that outputs a drive signal and a power conversion circuit (hereinafter referred to as a main amplifier) 7 that outputs high frequency power based on the drive signal from the drive circuit 9. The oscillation circuit 5 using the crystal unit X and the preamplifier 6 that amplifies the oscillation output of the oscillation circuit 5 are configured. The oscillation circuit 5, the preamplifier 6, and the main amplifier 7 operate by receiving power supply from a single DC power source E.
[0004]
The main amplifier 7 includes a so-called class D amplifier circuit in which two field effect transistors (hereinafter referred to as switching elements) Q1 and Q2 are connected in series, and have an inductor L2 and a capacitor C2. The secondary windings n21 and n22 of the transformer T1 are connected between the control terminals of the switching elements Q1 and Q2, respectively. The inductor L2 and the capacitor C2 constitute a resonance circuit. The output voltage of the preamplifier 6 is applied to the primary winding n1 of the transformer T1, and the switching elements Q1 and Q2 are driven through the secondary windings n21 and n22 of the transformer T1.
[0005]
In the conventional power supply device shown in FIG. 5, the oscillation circuit 5, the preamplifier 6, and the main amplifier 7 are all configured to operate by receiving power supply from a single DC power supply E. In addition, it is difficult to perform dimming control of the electrodeless discharge lamp 1 by changing the DC voltage, and there is an insufficient point in reducing variations in the output voltage of the main amplifier 7.
[0006]
Therefore, in the prior art, a power supply device as shown in FIG. 6 has been proposed (see, for example, JP-A-10-70887). In FIG. 6, components corresponding to those shown in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted.
In the conventional power supply device shown in FIG. 6, the output voltage obtained by rectifying the AC power supply AC by the rectifier DB1 via the filter circuit 20 is supplied to the first DC power supply E1, and the second DC is supplied via the diode D1. It is also input to the power source E2. The first DC power supply E1 is used as a drive power supply for the main amplifier 7, and the second DC power supply E2 is used as a drive power supply for the drive circuit 9.
[0007]
Further, in order to control the output voltage of the second DC power supply E2, a detection circuit 10 for detecting the voltage across the induction coil 2 is provided, and the detection output of the detection circuit 10 is the output of the second DC power supply E2. Input to the second control circuit 82.
[0008]
Here, the first DC power supply E1 includes a so-called boost chopper circuit as a DC stabilized power supply. The boost chopper circuit includes an inductor L11, a switching element Q11, a diode D11, a smoothing capacitor C11, and a first control circuit. 81. The first control circuit 81 detects the voltage across the smoothing capacitor C11 and controls the switching element Q11.
[0009]
Accordingly, in the first DC power supply E1, the output voltage obtained by rectifying the AC power supply AC by the rectifier DB1 is boosted to a high voltage by switching the switching element Q11 under the control of the first control circuit 81, and the input voltage The current distortion is improved.
[0010]
The second DC power supply E2 is a so-called step-down chopper circuit as a DC stabilized power supply. The step-down chopper circuit smoothes the output voltage of the rectifier DB1 and also functions as a noise filter and a switching element C13. Q12, inductor L12, diode D12, smoothing capacitor C12, and second control circuit 82 are included. The second control circuit 82 detects the voltage across the smoothing capacitor C12 and inputs a signal from the detection circuit 10 to control the switching element Q12.
[0011]
Accordingly, in the second DC power supply E2, the output voltage obtained by rectifying the AC power supply AC by the rectifier DB1 is stepped down to a low voltage by switching the switching element Q12 under the control of the second control circuit 82.
[0012]
Further, a filter circuit 20 is inserted on the AC input side of the rectifier DB1. By the action of the filter 20, as shown in FIG. 7, the triangular wave current Id flowing through the input terminals of the first DC power supply E1 and the second DC power supply E2 is averaged to obtain a sine wave current Ie. The input current Iin from the power supply AC is brought close to a sine wave to reduce waveform distortion and improve the power factor.
[0013]
Here, the power supply apparatus shown in FIG. 6 uses the first DC power supply E1 as the drive power supply for the main amplifier 7, and uses the second DC power supply E2 as the drive power supply for the drive circuit 9. The DC power supplies E1 and E2 are properly used for each of the circuits 7 and 9. For this reason, compared with the power supply device shown in FIG. 5, the circuit efficiency can be prevented from being lowered, the dimming control of the electrodeless discharge lamp 1 as a load is easy, and a sufficient voltage can be obtained at the start. There are various advantages such as the variation in the output voltage of the main amplifier 7 can be reduced.
[0014]
[Problems to be solved by the invention]
By the way, in the conventional power supply device shown in FIG. 6, the second DC power supply E2 is provided with a capacitor C13 that smoothes the output voltage of the rectifier DB1 and also serves as a noise filter. When the capacity is relatively large, the entire waveform of the input current Iin of the AC power supply AC is distorted, and as a result, the power factor decreases.
[0015]
On the contrary, when the capacitance of the capacitor C13 is reduced, the value of the input voltage decreases and the input energy becomes insufficient near the valley where the voltage at the full-wave rectified voltage of the output of the rectifier DB1 approaches zero. As a result, the current supplied from the AC power supply AC temporarily increases, and the input current Iin has a waveform as shown in FIG.
[0016]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply device in which the input current distortion of an AC power supply is small and the power factor is high.
[0017]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, a rectifier that rectifies alternating current, and first and second power supply circuits that are connected to the subsequent stage of the rectifier and generate different high and low direct current voltages, A drive circuit that outputs a drive signal based on an output of an oscillator using the second power supply circuit as a power supply, and a switching element is driven by the drive signal of the drive circuit using the first power supply circuit as a power supply to output high-frequency power The first power supply circuit is a step-up / step-down chopper circuit, and the second power supply circuit is a step-down chopper circuit, which is connected to the input terminal of the second power supply circuit. , together with the output voltage of the rectifier, wherein the output voltage of the first power supply circuit which is another DC voltage for the energy replenishment is to be applied to this
[0018]
According to a second aspect of the present invention, the drive circuit includes a preamplifier that amplifies the oscillation output of the oscillator and outputs a drive signal.
[0019]
According to a third aspect of the present invention, the power conversion circuit is a class D or class E amplifier circuit.
[0020]
According to a fourth aspect of the present invention , an electrodeless discharge lamp is connected to the subsequent stage of the power conversion circuit.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
FIG. 1 is a circuit diagram of the power supply device according to the first embodiment. Components corresponding to those of the prior art shown in FIG. Detailed description of the same configuration and parts having the same functions and effects as those of the prior art will be omitted.
[0029]
Also in the power supply device of the first embodiment, as in the prior art, a high-frequency power source 3 that uses the electrodeless discharge lamp 1 as a load and supplies high-frequency power to the electrodeless discharge lamp 1 via the induction coil 2, and the high-frequency power source 3 The first and second DC power supplies E1 and E2, the rectifier DB1, the filter circuit 20, and the detection circuit 10 that supply power to the main part are configured as main parts. The high frequency power supply 3 is common in that it includes a drive circuit 9 including an oscillator and a preamplifier (not shown) and a main amplifier 7 as a power conversion circuit.
[0030]
The power supply device according to the first embodiment is characterized in that the first DC power supply E1 is constituted by a so-called step-up / step-down chopper circuit as a DC stabilized power supply, and the output voltage of the first DC power supply E1 is a diode D2. It is comprised so that it may apply to the input terminal of 2nd DC power supply E2 via. The second DC power supply E2 is composed of a step-down chopper circuit having the same configuration as that of the conventional case shown in FIG.
[0031]
The step-up / step-down chopper circuit as the first DC power source E1 includes switching elements Q21 and Q22, inductors L21, diodes D21 and D22, a capacitor C21, a drive transformer T2, a control circuit 81, and a smoothing capacitor C11. The operation of such a step-up / step-down chopper circuit is described in, for example, Japanese Patent Application Laid-Open No. 5-130771, and is not described here.
[0032]
In the direct-current power supply of the first embodiment, the output voltage of the first direct-current power supply E1 is applied to the input terminal of the second direct-current power supply E2 via the diode D2, so that the full-wave rectified waveform of the output of the rectifier DB1 is When the value of the input voltage tends to decrease near the valley, the shortage of the voltage is supplemented by the output voltage of the first DC power supply E1. For this reason, the situation where input energy is insufficient in the second DC power supply E2 does not occur.
[0033]
Accordingly, the function of the capacitor C13 at the input terminal of the second DC power supply E2 can be reduced, that is, the capacity of the capacitor C13 can be set relatively small, and the cost and size of the parts can be reduced. . In addition, since the entire waveform of the input current Iin of the AC power supply AC as shown in FIG. 8 is not distorted, a high power factor can be obtained.
[0034]
In addition, since the first and second DC power supplies E1 and E2 are each configured by a non-insulated chopper circuit that does not use a transformer, compared to an insulated DC stabilized power circuit that uses a transformer. Increases circuit efficiency.
[0035]
In the first embodiment, the first DC power source E1 is composed of the step-up / step-down chopper circuit, but a step-up chopper circuit may be used. The main amplifier 7 is a class D amplifier circuit, but may be a so-called class E amplifier circuit. As in the case of class D, the class E amplifier circuit can achieve high efficiency even when the load operates at a very high frequency like the electrodeless discharge lamp 1.
[0036]
Further, in the case of a light source having a very long life like the electrodeless discharge lamp 1, it is desirable that the lighting device has a long life as well. As the first embodiment, by the first and second direct-current power supply E1, E2 and the main amplifier 7 is high efficiency, since wear in it to increase the component life is suppressed heat generation of the apparatus Can fully meet the above requirements.
[0037]
[Embodiment 2]
FIG. 2 is a circuit configuration diagram of the power supply device according to the second embodiment, and components corresponding to those in the first embodiment shown in FIG. Detailed description of the same configuration and the same function and effect as those of the first embodiment will be omitted.
[0038]
The power supply device according to the second embodiment is characterized in that a secondary winding L22 is provided for an inductor L21 in a step-up / step-down chopper that is a first DC power supply E1, and a voltage generated in the secondary winding L22 is converted to a diode. It is configured to be applied to the input terminal of the second DC power supply E2 via D2.
[0039]
In the second embodiment, an AC voltage is generated in the secondary winding L22 provided for the inductor L21 of the first DC power supply E1 in accordance with the switching operation of the switching elements Q21 and Q22. Is rectified by the diode D2 and then applied to the second DC power supply E2.
[0040]
Therefore, in the case of the second embodiment, although the degree of smoothing of the voltage applied from the first DC power supply E1 to the second DC power supply E2 via the diode D2 is somewhat inferior to that of the first embodiment, The same effect as in the first embodiment can be obtained.
[0041]
[Embodiment 3]
FIG. 3 is a circuit configuration diagram of the power supply device according to the third embodiment, and components corresponding to those in the first embodiment shown in FIG. Detailed description of the same configuration and the same function and effect as those of the first embodiment will be omitted.
[0042]
A feature of the power supply device according to the third embodiment is that the output voltage of the second DC power supply E2 is configured to be applied to the input terminal of the second DC power supply E2 via the diode D2.
[0043]
In the case of the third embodiment, when the value of the input voltage tends to decrease near the valley in the full-wave rectified waveform of the output of the rectifier DB1, the shortage of the voltage causes the diode D2 from the second DC power source E2. It is replenished by the output voltage fed back through. For this reason, since the situation where input energy is insufficient in the second DC power supply E2 does not occur, the same effect as in the first embodiment can be obtained.
[0044]
[Embodiment 4]
FIG. 4 is a circuit configuration diagram of the power supply device according to the fourth embodiment, and components corresponding to those in the first embodiment shown in FIG. Detailed description of the same configuration and the same function and effect as those of the first embodiment will be omitted.
[0045]
The power supply device according to the fourth embodiment is characterized in that a DC voltage from another third DC power supply E3 arranged outside the device is applied to the input terminal of the second DC power supply E2 via the diode D2. It is that.
[0046]
Also in the case of the fourth embodiment, when the value of the input voltage tends to decrease in the vicinity of the valley in the full-wave rectified waveform of the output of the rectifier DB1, the shortage of the voltage is generated from another third DC power supply E3. It is supplemented by the output voltage supplied via the diode D2. For this reason, since the situation where input energy is insufficient in the second DC power supply E2 does not occur, the same effect as in the first embodiment can be obtained.
[0047]
【The invention's effect】
According to the present invention, since the output voltage of the first DC power supply is applied to the input terminal of the second DC power supply, the energy of the input is also near the valleys in the full-wave rectified waveform of the output of the rectifier. Since there is no shortage and the entire waveform of the input current of the AC power supply is not distorted, the power factor is increased.
Furthermore, the capacitance of the capacitor at the input end of the second DC power supply can be made relatively small, and the cost and size of the parts can be reduced.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram of a power supply device according to a first embodiment of the present invention.
FIG. 2 is a circuit configuration diagram of a power supply device according to a second embodiment of the present invention.
FIG. 3 is a circuit configuration diagram of a power supply device according to a third embodiment of the present invention.
FIG. 4 is a circuit configuration diagram of a power supply device according to a fourth embodiment of the present invention.
FIG. 5 is a circuit configuration diagram showing an example of a conventional power supply device.
FIG. 6 is a circuit configuration diagram of another conventional power supply apparatus.
FIG. 7 is a waveform diagram for explaining the action of the filter circuit on the input current from the AC power supply.
FIG. 8 is a waveform diagram of a current supplied from an AC power supply AC.
[Explanation of symbols]
1 Electrodeless discharge lamp 2 Induction coil 3 High frequency power supply 4 Matching circuit 5 Oscillation circuit 7 Power conversion circuit (main amplifier)
9 drive circuit 10 detection circuit E1 first DC power supply E2 second DC power supply DB1 rectifier 20 filter circuit L2 secondary winding of inductor

Claims (4)

  A rectifier that rectifies alternating current, first and second power supply circuits that are respectively connected to subsequent stages of the rectifier and generate different high and low DC voltages, and driving based on the output of an oscillator using the second power supply circuit as a power source A power supply device comprising: a drive circuit that outputs a signal; and a power conversion circuit that outputs a high-frequency power by driving a switching element by a drive signal of the drive circuit using the first power supply circuit as a power supply. The power supply circuit is a step-up / step-down chopper circuit, and the second power supply circuit is a step-down chopper circuit, and the input terminal of the second power supply circuit is supplied with energy output different from this together with the output voltage of the rectifier. An output voltage of the first power supply circuit, which is a direct current voltage, is applied. The drive circuit includes a power supply device according to claim 1 wherein a pre-amplifier for outputting a drive signal by amplifying the oscillation output of the oscillator.   The power supply device according to claim 1, wherein the power conversion circuit is a class D or class E amplifier circuit.   The power supply device according to any one of claims 1 to 3, wherein an electrodeless discharge lamp is connected to a subsequent stage of the power conversion circuit.

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