JP2004253323A - Electrodeless discharge lamp, electrodeless discharge lamp lighting device, and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce fluctuation of a light output caused by fluctuation of ambient temperature with a simple structure. <P>SOLUTION: This electrodeless discharge lamp is provided with an almost spherical bulb 1 having a hollow part 2 with a reverse U-shaped cross section, wherein a discharge gas is filled, a cylindrical core 3 of magnetic materials, which is disposed in the hollow part 2, and an induction coil 4 wound around the core 3, to which high frequency power is supplied. The core 3 is structured by continuously providing a plurality of magnetic materials 3a, 3b and 3c having different curie temperatures in the axial direction of the induction coil 4. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrodeless discharge lamp that emits light by applying a high-frequency electromagnetic field to a bulb having a discharge gas sealed therein, an electrodeless discharge lamp lighting device for lighting the electrodeless discharge lamp, and an electrodeless discharge lamp and an electrodeless discharge lamp The present invention relates to a lighting device provided with a lighting device.
[0002]
[Prior art]
As a conventional example of this kind, there is one described in JP-A-2001-332220. As shown in FIG. 8, the lighting device includes a bulb J1, an induction coil J2 for generating an electromagnetic field inside the bulb J1, and a power supply J3 for supplying power to the induction coil J2. A discharge gas such as an inert gas or metal vapor is sealed in the bulb J1, and an electromagnetic field having a frequency of 50 kHz or more and 1 MHz or less is generated by the induction coil J2.
[0003]
The power supply J3 includes a high-frequency power supply circuit J3, and is connected to a power line via a base J7. The power supplied from the power line is converted into, for example, power having a frequency of 50 kHz or more and 1 MHz or less by switching a switching element inside the high-frequency power supply circuit J3.
[0004]
The high frequency power supply circuit J3 is electrically connected to the induction coil J2 via the matching circuit J4. The matching circuit J4 has a function of matching the impedance of the high-frequency power supply circuit J3 and the impedance of the induction coil J2 and efficiently supplying the power output from the high-frequency power supply circuit J3 to the induction coil J2. The induction coil J2 is composed of a core J2a and a winding J2b. When power is supplied from the high-frequency power supply circuit J3 to the induction coil J2, an electromagnetic field generated by the induction coil J2 is provided inside the valve J1. Energy is induced, and a ring-shaped discharge plasma J6 is generated. Ultraviolet light or visible light is generated from the discharge plasma J6, thereby obtaining an optical output.
[0005]
The valve J1 has a cavity J8, which is a gap, substantially along the center axis of the valve J1, and an induction coil J2 is arranged in the cavity J8. That is, the induction coil J2 is inserted into the recess J8 formed at the center of the bulb by making the outer wall of the bulb J1 concave, and is arranged near the bulb J1. The high-frequency power supply circuit J3 and the matching circuit J4 electrically connected to the induction coil J2 are housed in a circuit case J5. In the present embodiment, the lighting device is configured as a bulb-type fluorescent lamp in which a bulb J1 in which an induction coil J2 is inserted into a cavity J8, a circuit case J5, and a base J7 are integrated.
[0006]
The core J2a is composed of Mn-Zn-based polycrystalline ferrite, and the Mn-Zn-based polycrystalline ferrite constituting the core J2a has a Curie temperature of 270 ° C or higher. That is, as the magnetic material forming the core J2a, Mn—Zn-based ferrite having a Curie temperature of 270 ° C. or higher is used.
[0007]
As described above, in the above-described configuration, since the core J2a is made of Mn—Zn-based polycrystalline ferrite having a Curie temperature of 270 ° C. or higher, the illumination capable of starting and maintaining the discharge plasma J6 in the frequency range of 50 kHz to 1 MHz. Equipment is provided.
[0008]
[Patent Document 1]
JP 2001-332220A
[0009]
[Problems to be solved by the invention]
The light output from the bulb J1 changes greatly depending on the state of the discharge gas in the bulb J1. When the composition and pressure of the discharge gas are determined in an optimal state based on the design values and sealed, and put on the market as a product, the light output greatly changes depending on the ambient temperature. Therefore, in commercializing such a lighting device, it is necessary to make the light output substantially constant with respect to a change in ambient temperature.
[0010]
Here, the path of the magnetic flux in this lighting device is considered. As shown in FIG. 9, the magnetic flux J9 generated by the induction coil J2 passes through the inside of the core J2a, passes near the end face of the winding J2b in the winding axis direction, and is emitted to the space. From there, it passes through the bulb J1, excites the internal discharge plasma J6, and returns to the inside of the core J2a again near the other end face in the winding axis direction of the winding J2b.
[0011]
From this, it is conceivable to change the positional relationship between the magnetic flux J9 generated by the induction coil J2 and the discharge plasma J6 in the bulb J1 as one of means for changing the light output.
[0012]
Here, the light output from the bulb J1 may increase when the temperature becomes high. When the core J2a is made of a single magnetic material, the path of the magnetic flux J9 passing through the core J2a is substantially constant even when the temperature of the core J2a changes. For this reason, the light output also increases as the temperature of the bulb J1 increases, and it may not be possible to make the light output substantially constant.
[0013]
The present invention has been made in view of the above problems, and has as its object the purpose of lighting an electrodeless discharge lamp and an electrodeless discharge lamp with a simple configuration and a small change in light output due to a change in ambient temperature. It is an object of the present invention to provide an electrodeless discharge lamp lighting device and an illumination device including the electrodeless discharge lamp and the electrodeless discharge lamp lighting device.
[0014]
[Means for Solving the Problems]
2. An electrodeless discharge lamp according to claim 1, wherein the discharge gas is enclosed therein, and the bulb has a substantially spherical shape having a cavity having an inverted U-shaped cross section, and a columnar core made of a magnetic material disposed in the cavity. And an induction coil wound around the core and supplied with high-frequency power, wherein the core is formed by connecting a plurality of magnetic materials having different Curie temperatures along the winding axis direction of the induction coil. Is what you do.
[0015]
The light output of an electrodeless discharge lamp may increase at high temperatures. In such a case, if the core is made of a plurality of magnetic materials, the magnetic permeability decreases in order from the magnetic material having the lowest Curie temperature even if the temperature increases, and the light output increases. And the light output is made substantially constant.
[0016]
An electrodeless discharge lamp according to a second aspect is characterized in that, in the electrodeless discharge lamp according to the first aspect, the induction coil is not wound around the core having the lowest Curie temperature.
[0017]
In such an electrodeless discharge lamp, the coil is not wound around a core whose magnetic permeability tends to decrease when the temperature of the electrodeless discharge lamp becomes high, thereby suppressing power loss in the coil.
[0018]
The electrodeless discharge lamp according to claim 3 is the electrodeless discharge lamp according to claim 1 or 2, wherein the core having the lowest Curie temperature is disposed at a position farthest from the opening of the cavity. It is characterized by the following.
[0019]
In such an electrodeless discharge lamp, the temperature rise of the electrodeless discharge lamp is transmitted to the core regardless of the direction in which the electrodeless discharge lamp is installed.
[0020]
An electrodeless discharge lamp according to claim 4, wherein the discharge gas is sealed therein and a substantially spherical bulb having an inverted U-shaped cross-section which is provided continuously with each other, and a mutual cavity within the bulb. Exhaust pipe formed between the portions, a mercury amalgam disposed in the exhaust pipe, a columnar core made of a magnetic material disposed in the hollow portion, and an induction coil wound around the core and supplied with high-frequency power Wherein the core is formed by connecting a plurality of magnetic materials having different Curie temperatures along the winding axis direction of the induction coil.
[0021]
Even in such an electrodeless discharge lamp, since the core is composed of a plurality of magnetic materials, even if the temperature increases, the magnetic permeability decreases in order from the magnetic material having the lowest Curie temperature. Thus, an increase in light output is suppressed, and the light output is made substantially constant.
[0022]
An electrodeless discharge lamp according to a fifth aspect of the present invention is the electrodeless discharge lamp according to the fourth aspect, wherein the magnetic material having the lowest Curie temperature is disposed near the mercury amalgam. .
[0023]
The magnetic material having the lowest Curie temperature has the lowest permeability first when the electrodeless discharge lamp is heated to a high temperature, and does not perform the function of the core. Then, heat generation due to power loss from the magnetic material is suppressed, and the temperature rise of the mercury amalgam disposed near the magnetic material is suppressed. When the temperature rise is suppressed, the mercury vapor pressure from the mercury amalgam decreases, and the light output is suppressed.
[0024]
The electrodeless discharge lamp according to claim 6 is the electrodeless discharge lamp according to any one of claims 1 to 5, wherein the lowest Curie temperature is a Curie temperature of 200 ° C or less. is there.
[0025]
In such an electrodeless discharge lamp, a material having a heat resistance of about 200 ° C. can be used for the induction coil.
[0026]
An electrodeless discharge lamp according to claim 7 is the electrodeless discharge lamp according to any one of claims 1 to 5, wherein the magnetic material having the lowest Curie temperature includes manganese and zinc. Things.
[0027]
The light output of an electrodeless discharge lamp may decrease at low temperatures. When such a material is used as the magnetic material of the core, the difference in the magnetic permeability between the low temperature and the high temperature of the electrodeless discharge lamp can be increased. At low temperatures when the light output of the electrodeless discharge lamp decreases, the magnetic permeability of the core increases, thereby increasing the light output of the electrodeless discharge lamp. At high temperatures where the light output increases, the magnetic permeability of the core decreases. Reduces the light output and makes the light output approximately constant from low to high temperatures.
[0028]
An electrodeless discharge lamp lighting device according to an eighth aspect of the present invention includes an electrodeless discharge lamp according to any one of the first to seventh aspects, a high-frequency power supply that supplies high-frequency power to an induction coil and has a variable supply power, A detection circuit for detecting the inductance of the coil is provided, and when the inductance falls below a predetermined value, control is performed to reduce the supplied power.
[0029]
In such an electrodeless discharge lamp lighting device, when the magnetic permeability of the core having the lowest Curie temperature decreases, the decrease in the inductance of the induction coil due to the decrease in the magnetic permeability is detected, and the discharge to the electrodeless discharge lamp is performed. Reduce power supply.
[0030]
According to a ninth aspect of the present invention, there is provided an electrodeless discharge lamp lighting device comprising: the electrodeless discharge lamp according to any one of the first to seventh aspects; A capacitive element connected in series with the coil; and a voltage detection circuit that detects a voltage between both ends of the capacitive element, and performs control to reduce supplied power when the detected voltage rises above a predetermined voltage. It is characterized by the following.
[0031]
When the electrodeless discharge lamp lighting device is abnormal, such as when excessive power is supplied to the electrodeless discharge lamp, the voltage across the induction coil may increase. In such a case, a voltage that reflects the voltage across the induction coil is detected, and control is performed to reduce the power supplied to the electrodeless discharge lamp.
[0032]
According to the electrodeless discharge lamp lighting device of the tenth aspect, in the electrodeless discharge lamp lighting device of the eighth or ninth aspect, instead of performing the control of reducing the supply power, the control of intermittently supplying the power is performed. It is characterized by performing.
[0033]
In such an electrodeless discharge lamp lighting device, control is performed to intermittently supply power to the electrodeless discharge lamp when the inductance is lowered or the electrodeless discharge lamp lighting device is abnormal.
[0034]
An illumination device according to an eleventh aspect includes the electrodeless discharge lamp lighting device according to any one of the eighth to tenth aspects, and lights the electrodeless discharge lamp according to any one of the first to seventh aspects. It is characterized by the following.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example 1)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the present embodiment, and FIG. 2 is a circuit diagram of the high-frequency power supply 12. FIG. 3 is a cross-sectional view of a lighting device provided with an electrodeless discharge lamp lighting device, and FIG. 4 shows a path of a magnetic flux J9. 5 shows a general relationship between the temperature of the induction coil 4 and the inductance of the induction coil 4. FIG. 6 shows the relationship between the temperature of the induction coil 4 and the inductance of the induction coil 4 in the present embodiment. Is shown.
[0036]
Hereinafter, the configuration of each unit will be described.
[0037]
The bulb 1 has a substantially spherical shape and has a discharge gas containing at least mercury and a rare gas sealed therein, and has a bottomed lower U-shaped cross section below the bulb 1. A cavity 2 is provided. The material of the bulb 1 is a translucent material such as quartz glass, and the discharge gas is mercury, a rare gas, and a metal halide. As an example, a xenon gas of about 300 Torr and a mixed gas of about 10 mg of sodium iodide, thallium iodide and indium iodide are used. Of course, another gas or metal may be used as the discharge gas to be filled. The inside of the bulb 1 is coated with a phosphor 10 and a protective film 11. The phosphor 10 converts ultraviolet light emitted from mercury into visible light. The material of the phosphor 10 is calcium halophosphate, red phosphor (Y, Gd) BO3: Eu, green phosphor. Certain CaPO4 and blue phosphor BaMgAll4O23: Eu are used. The protective film 11 improves the luminous flux maintenance factor of the bulb 1 by suppressing the reaction between mercury and quartz glass which is the material of the bulb 1. As a material of the protective film 11, fine particles such as alumina (Al2O3), silica (SiO2), titania (TiO2), ceria (CeO2), yttria (Y2O3), and magnesia (MgO) are used. The protective film 11 is preferably formed on the inner surface of the bulb 1 thinner than the phosphor 10 because it is desirable that the transmittance of the ordinary bulb 1 be higher. Further, the shape of the valve 1 does not have to be substantially spherical, and may be another shape such as a cylindrical shape.
[0038]
The induction coil 4 supplies a high-frequency electromagnetic field oscillating at 13.56 MHz to the discharge gas inside the bulb 1, and one of the coils is wound around a columnar core 3 described later along the column axis direction of the core 3. The other is connected to a high-frequency power supply 12 described later. Here, the induction coil 4 is formed by winding a strip made of copper or a copper alloy around the core 3 a predetermined number of times, and it is desirable to use a litz wire to suppress loss. Litz wire is a composite wire composed of twisted fine wires, and has a larger surface area than a single wire of the same thickness, so it is possible to minimize the increase in loss due to the skin effect and proximity effect of the winding at high frequencies. it can.
[0039]
As a material for covering the strip of the induction coil 4, a high heat-resistant fluororesin, a heat-resistant enameled wire, or a silicon-based resin, which is an insulator, is used.
[0040]
When the high-frequency power supply 12 operates, a high-frequency current flows through the induction coil 4, and a high-frequency electromagnetic field is generated around the induction coil 4. Next, electrons generated inside the bulb 1 are accelerated by the generated high-frequency electromagnetic field, and collide with atoms of the discharge gas to ionize the discharge gas, thereby generating new electrons. The electrons thus generated receive energy by a high-frequency electromagnetic field generated around the induction coil 4 and collide with the discharge gas atoms to give energy. The atoms in the discharge plasma J6 are ionized or excited. The excited atoms emit light when returning to the ground state. This light emission is used as light energy.
[0041]
The core 3 has a columnar shape with a substantially circular cross section, and is erected and fixed to the base 9 so that one end of the core 3 faces the center of the bulb 1 and the other end faces a base 9 described later inside the cavity 2. Have been. The core 3 is formed of three types of magnetic materials 3a, 3b, and 3c having different Curie temperatures (hereinafter, Curie temperatures of the magnetic materials 3a, 3b, and 3c are referred to as Ta, Tb, and Tc, respectively). , Ta>Tb> Tc. Here, the induction coil 4 is wound only on the magnetic materials 3a and 3b, and the induction coil 4 is not wound on the magnetic material 3c. Further, the magnetic material 3c is disposed on the innermost side of the cavity 2, which is the position farthest from the opening of the cavity 2, and the magnetic materials 3b and 3a are disposed in this order. Note that the order of the magnetic materials 3a and 3b may be changed. The innermost side of the cavity 2 is hardly affected by the outside air temperature from the opening of the cavity 2. For example, even when the electrodeless discharge lamp lighting device is placed sideways, the magnetic material 3 c The temperature of the valve 1 can be accurately reflected.
[0042]
As the material of the magnetic materials 3a and 3b, Mn-Zn-based polycrystalline ferrite having a Curie temperature of about 240 to 280C is used. When the bulb 1 is turned on at room temperature, the Curie temperature of about 240 to 280 ° C. is sufficient. However, when the temperature around the bulb 1 is higher than room temperature, or when the input power to the high-frequency power supply 12 is overloaded or the like. In consideration of the case where the current rises and the current flowing through the induction coil 4 increases, a Curie temperature of 300 ° C. or more may be used in consideration of a design margin.
[0043]
As a material of the magnetic material 3c, Mn (manganese) -Zn (zinc) -based ferrite having a Curie temperature of 200 ° C. or less is used. Here, the Mn—Zn-based ferrite contains Fe (iron), Mn, and Zn as main composition components excluding the oxygen element, and is obtained by synthesizing and sintering respective oxides of Fe, Mn, and Zn. A main oxide for forming the Mn-Zn-based ferrite is, for example, Fe2O3, MnO, or ZnO.
[0044]
In the present embodiment, Mn-Zn-based polycrystalline ferrite is used as the material of the magnetic material 3c. However, Mn-Zn-based single-crystal ferrite may be used as long as it has a Curie temperature of 200 ° C or less. Alternatively, Ni (nickel) -Zn based polycrystalline or single crystal ferrite may be used.
[0045]
When such a magnetic material having a Curie temperature of 200 ° C. or less is used, a low heat-resistant material can be used as a material for covering the strip of the induction coil 4, and an expensive high heat-resistant fluororesin or the like is used. You don't have to.
[0046]
The member 5 has a columnar shape with a substantially circular cross section, and is provided so that the core 3 contacts the outside of the member 5.
[0047]
The base 9 is a casing formed of aluminum die-casting, having a substantially convex cross section, and having an opening on the upper surface. The member 5 described above is erected and fixed to the bottom surface of the base 9 so as to face the center of the valve 1.
[0048]
The high-frequency power supply 12 has its output terminals (both ends of the matching circuit 17) connected to the above-described induction coil 4, and has a configuration as shown in FIG.
[0049]
That is, the high-frequency power supply 12 rectifies the AC voltage from the commercial AC power supply AC into a pulsating DC voltage and outputs the rectified DC voltage, and converts the pulsating DC voltage from the rectifying circuit DB into a desired DC voltage. And a chopper control circuit 7 for controlling the frequency of the switching element Q1 of the chopper circuit 15, and the DC voltage E from the capacitor C1 is turned into a rectangular wave voltage by the on / off operation of the switching elements Q2 and Q3. A power conversion circuit 16 for conversion, a drive circuit 8 for transmitting a drive signal to the switching elements Q2 and Q3 of the power conversion circuit 16, and a control clock signal to the drive circuit 8 for controlling the frequencies of the switching elements Q2 and Q3. A frequency control circuit 6 for transmission, an inductor L2 and a capacitor C2 forming a series resonance circuit, When the impedance between the conversion circuit 16 and the induction coil 4 is matched and the high frequency power from the power conversion circuit 16 is efficiently transmitted to the induction coil 4, the induction coil 4 connected to both ends of the matching circuit 17 A voltage detection circuit 20 for detecting a voltage between both ends of a capacitor C4 of a capacitive element included in the microcomputer 17; a microcomputer 19 for receiving a detection voltage signal from the voltage detection circuit 20 and controlling a control clock signal output from the frequency control circuit 6; , An IPD (intelligent power device) step-down circuit 15 for supplying power to the frequency control circuit 6, the chopper control circuit 7, and the like.
[0050]
Here, the voltage detection circuit 20 detects a change in the voltage across the capacitor C4, that is, a change in the voltage V02 across the induction coil 4. This voltage detection circuit 20 includes resistors R92 to R94, diodes D92 and D93, capacitors C91 to C95, a Zener diode ZD91, and a transistor Q91.
[0051]
The IPD step-down circuit 15 converts the DC voltage E into a DC voltage of, for example, 15 V, and supplies power to the frequency control circuit 6, the chopper control circuit 7, the drive circuit 8, and the microcomputer 19. The IPD step-down circuit 15 includes a resistor R41, diodes D41 and D42, capacitors C41 to C44, an inductor L41, zener diodes ZD41 and ZD42, a photocoupler PC41, and an IC41.
[0052]
Further, the microcomputer 19 receives the off signal and controls the frequency of the reference clock signal of the frequency control circuit 6 when the transistor Q91 is off when the voltage across the capacitor C4 decreases.
[0053]
Of course, the configuration of the high-frequency power supply 12 is not limited to this as long as it supplies a high-frequency electromagnetic field of 13.56 MHz to the discharge gas inside the bulb 1.
[0054]
An electrodeless discharge lamp lighting device is constituted by the high frequency power supply 12 and the electrodeless discharge lamp, and as an illumination device provided with the electrodeless discharge lamp lighting device for lighting the electrodeless discharge lamp, for example, a lighting device shown in FIG. Is mentioned.
[0055]
The shield case 13 covers the upper part of the bulb 1, and radiation noise from the electrodeless discharge lamp is absorbed by the shield case 13. Of course, the lighting device for lighting the electrodeless discharge lamp is not limited to this.
[0056]
Next, an operation during lighting of the electrodeless discharge lamp will be described.
[0057]
When the electrodeless discharge lamp continues to be lit for, for example, thousands of hours and the temperature of the core 3 or the like increases and the temperature of the entire electrodeless discharge lamp increases, the light output may increase. In such a case, the magnetic material 3c having the lowest Curie temperature reaches the Curie temperature, and the magnetic permeability decreases. Then, the magnetic material 3c loses the function as the core, and only the magnetic materials 3a and 3b function as the core. That is, the length of the magnetic material is shortened, and as shown in FIG. 4, the magnetic path of the magnetic flux J9 generated by the induction coil 4 is shortened, and the coupling between the magnetic flux J9 and the discharge plasma J6 is reduced. That is, power is not efficiently transmitted to the discharge plasma J6, and the light output is reduced. Here, since the induction coil 4 is not wound around the magnetic material 3c, even if the magnetic permeability of the magnetic material 3c decreases, the power loss in the induction coil 4 does not increase so much. Does not significantly increase the power loss of the entire electrodeless discharge lamp lighting device.
[0058]
In particular, in the present embodiment, Mn-Zn-based ferrite is used as the material of the magnetic material 3c, and the Mn-Zn-based ferrite has a relative magnetic permeability of 1000 or more at a low temperature and a large number of Although the magnetic flux penetrates, the relative magnetic permeability sharply decreases when the temperature exceeds the Curie temperature, so that when the electrodeless discharge lamp becomes high temperature and the light output is about to increase, the increase in the light output is effectively suppressed. be able to.
[0059]
In this way, even if the electrodeless discharge lamp rises, the increase in light output is suppressed, and the light output can be made substantially constant even if the temperature of the electrodeless discharge lamp rises.
[0060]
Here, according to the experimental results of the applicant, when a magnetic material having a low magnetic permeability is provided in the core 3 around which the induction coil 4 is wound, the reactance component and the resistance component of the induction coil 4 It was found that the Q value representing the ratio decreased by more than 10% or more. In such a state, the power loss in the induction coil 4 increases, and the temperature of the induction coil 4 and eventually the temperature of the entire electrodeless discharge lamp increase.
[0061]
In the present embodiment, as described above, the induction coil 4 is not wound around the magnetic material 3c having the lowest Curie temperature, thereby preventing a decrease in magnetic permeability due to a rise in temperature without taking measures against temperature with a complicated configuration. be able to.
[0062]
In the present embodiment, the voltage detection circuit 20 detects the voltage between both ends of the induction coil 4.
[0063]
When the temperature of the electrodeless discharge lamp becomes high and the temperature of the magnetic material exceeds the Curie temperature, the magnetic permeability of the magnetic material decreases, and the inductance of the induction coil 4 wound around the magnetic material rapidly decreases as shown in FIG. I do.
[0064]
When different magnetic materials are brought into contact with each other as in this embodiment and connected in series, as shown in FIG. 6, the magnetic material 3c having the lowest Curie temperature decreases in permeability in order. As a result, the inductance of the induction coil 4 gradually decreases. When the inductor of the induction coil 4 decreases, the voltage generated across the induction coil 4 decreases, and the voltage of the capacitor C93 does not reach the on-voltage of the Zener diode ZD91, so that the transistor Q91 is turned off. Then, the microcomputer 19 receives the off signal of the transistor Q91, increases the frequency of the reference clock signal of the frequency control circuit 6, and can reduce the light output of the electrodeless discharge lamp.
[0065]
That is, in the present embodiment, the relative permeability of the magnetic material 3c having the lowest Curie temperature is reduced, and in addition to suppressing the increase in the light output of the electrodeless discharge lamp, the induction coil 4c due to the reduced relative permeability is reduced. Since the decrease in the inductance of the electrodeless discharge lamp is detected and the increase in the light output of the electrodeless discharge lamp is suppressed, the light output of the electrodeless discharge lamp can be reduced more reliably.
[0066]
Here, in the configuration of the present embodiment, since the capacitor C4 of the matching circuit 17 is also used as a part of the voltage detection circuit 20, an additional circuit for separately detecting a decrease in the inductor of the induction coil 4 is separately provided. There is no need to provide In particular, since a relatively high voltage is applied to the capacitor C4, if a new detection circuit is separately provided in order to detect a decrease in the inductor of the induction coil 4, a high withstand voltage element is required. In the embodiment, such a need is eliminated, and the cost of the electrodeless discharge lamp lighting device can be reduced.
[0067]
In addition, when a separate inductor detection circuit for the induction coil 4 is provided, not shown, for example, a source resistance may be provided between the switching element Q3 and circuit ground. By measuring the voltage across the source resistor, it is possible to indirectly detect a drop in the inductor of the induction coil 4, and since only a relatively low voltage of about several volts is applied across such a source resistor, Without using a high withstand voltage element, it is possible to detect a decrease in the inductor of the induction coil 4 and reduce the light output of the electrodeless discharge lamp. Of course, the current flowing through the source resistance may be detected. Furthermore, although the power consumption of the electrodeless discharge lamp lighting device decreases due to the decrease in the inductor, the electrical characteristics that can indirectly detect the decrease in the inductor are not only those described above, but also other electrical characteristics. (High-pressure discharge lamp current, high-pressure discharge lamp power, and further, luminous efficiency of the high-pressure discharge lamp (lumen per watt)), optical characteristics (illuminance or color temperature of the high-pressure discharge lamp, and further, luminance, luminous flux, luminous intensity), or Temperature characteristics (the coldest point temperature of the high pressure discharge lamp, the tube wall temperature or the base temperature).
[0068]
In this embodiment, the light output of the electrodeless discharge lamp is reduced by increasing the frequency of the reference clock signal of the frequency control circuit 6 and increasing the drive frequency of the switching elements Q2 and Q3. The duty of the signal may be increased to increase the duty of the switching elements Q2 and Q3 to reduce the light output of the electrodeless discharge lamp. Alternatively, the frequency of the switching element Q1 included in the chopper circuit 15 may be controlled and the chopper circuit 15 may be controlled. May be reduced to reduce the light output of the electrodeless discharge lamp.
[0069]
When the light output of the electrodeless discharge lamp is reduced by the above-described method, the light output of the electrodeless discharge lamp certainly decreases, but the impedance of the discharge plasma J6 decreases with the decrease of the light output of the electrodeless discharge lamp. And the power loss in the magnetic material may increase.
[0070]
In such a case, the frequency of the reference clock signal may be intermittently oscillated, and the electrodeless discharge lamp may be intermittently oscillated. When the electrodeless discharge lamp is oscillated intermittently instead of continuously, power loss in the magnetic material can be suppressed.
[0071]
Note that, depending on the type of the discharge gas, when the impedance of the discharge plasma J6 increases with a decrease in the light output of the electrodeless discharge lamp, the voltage applied to both ends of the induction coil 4 may increase.
[0072]
In such a case, the voltage of the capacitor C92 obtained by dividing the voltage applied to the capacitor C4 exceeds the on-voltage of the Zener diode ZD91, and when the transistor Q91 is turned on, the reference clock signal of the frequency control circuit 6 is turned off. The microcomputer 19 may be programmed to increase the frequency.
[0073]
(Example 2)
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a sectional view of the present embodiment. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0074]
The difference between the electrodeless discharge lamp shown in FIG. 7 and the electrodeless discharge lamp shown in FIG. 1 is that, instead of the electrodeless discharge lamp shown in FIG. It has cavities 21a and 21b which are connected to each other and has an inverted U-shaped cross section, and the mercury amalgam 23 is disposed in an exhaust pipe 22 formed between the cavities 21a and 21b. is there. A core made of two kinds of magnetic materials 3a and 3c (Ta> Tc) having different Curie temperatures so as to surround the exhaust pipe 22 along the axial direction of the exhaust pipe 22 in the hollow portions 21a and 21b. 3 are provided. Further, an induction coil 4 is wound along the column axis direction of the core 3. Here, the mercury amalgam 23 is provided below the exhaust pipe 22, and the magnetic material 3 c is provided beside the mercury amalgam 23.
[0075]
That is, the magnetic material 3c having a low Curie temperature is disposed near the mercury amalgam 23.
[0076]
The mercury amalgam 23 is an alloy formed by reacting a base metal such as Bi (bismuth) -In (indium) or Pb (lead) -Bi-Sn (tin) with mercury. The temperature characteristic of the vapor pressure shifts to a higher temperature side. Therefore, an optimal mercury vapor pressure can be obtained even when the electrodeless discharge lamp becomes hot during normal lighting.
[0077]
Although not shown, a metal that is not easily combined with mercury, for example, a nickel-plated iron plate or a stainless steel plate whose surface is mechanically roughened is disposed above the mercury amalgam 23. If provided, a part of the amalgam mercury that has become a gas during normal lighting is trapped in this metal part, so that the light output quickly rises at the time of restart or the like.
[0078]
As described above, according to the configuration of the present embodiment, when the temperature of the electrodeless discharge lamp becomes high, the magnetic permeability of the magnetic material 3c having the lowest Curie temperature is reduced most quickly, and the magnetic material 3c does not function as a core. Then, heat generation due to power loss from the magnetic material is suppressed, and the temperature rise of the mercury amalgam 23 disposed near the magnetic material 3c is suppressed. When the temperature rise of the mercury amalgam 23 is suppressed, the mercury vapor pressure from the mercury amalgam 23 decreases, and the increase in light output can be suppressed.
[0079]
As described above, if the magnetic material 3c having a low Curie temperature is disposed in the vicinity of the mercury amalgam 23 having a great influence on the discharge gas in the bulb 1, an increase in light output due to a rise in the temperature of the electrodeless discharge lamp is prevented. It can be suppressed accurately.
[0080]
The functions, effects, and the like not specifically mentioned in the above description are the same as those in the first embodiment.
[0081]
【The invention's effect】
In the electrodeless discharge lamp according to the first aspect, the core has a plurality of magnetic materials having different Curie temperatures arranged continuously along the winding axis direction of the induction coil. Even when the temperature increases, the magnetic permeability decreases in order from the magnetic material having the lowest Curie temperature even when the temperature increases, and the optical output increases. The light output can be suppressed and the light output can be made substantially constant.
[0082]
In the electrodeless discharge lamp according to the second aspect of the present invention, since the induction coil is not wound around the core having the lowest Curie temperature in the electrodeless discharge lamp according to the first aspect, the temperature of the electrodeless discharge lamp becomes high. Sometimes, the coil is not wound around the core whose permeability is apt to decrease, so that the power loss in the coil can be suppressed.
[0083]
In the electrodeless discharge lamp according to the third aspect, in the electrodeless discharge lamp according to the first or second aspect, the core having the lowest Curie temperature is disposed at a position farthest from the opening of the cavity. The temperature rise of the electrodeless discharge lamp can be transmitted to the core regardless of the direction in which the electrodeless discharge lamp is installed.
[0084]
An electrodeless discharge lamp according to claim 4, wherein the discharge gas is sealed therein and a substantially spherical bulb having an inverted U-shaped cross-section which is provided continuously with each other, and a mutual cavity within the bulb. Exhaust pipe formed between the portions, a mercury amalgam disposed in the exhaust pipe, a columnar core made of a magnetic material disposed in the hollow portion, and an induction coil wound around the core and supplied with high-frequency power The core is provided with a plurality of magnetic materials having different Curie temperatures continuously arranged along the winding axis direction of the induction coil. Even when the light output of the electrode discharge lamp increases, the core is composed of a plurality of magnetic materials, and even if the temperature increases, the magnetic permeability decreases in order from the magnetic material having the lowest Curie temperature. Suppress the increase in light output and keep the light output approximately constant It can be.
[0085]
The electrodeless discharge lamp according to claim 5 is the electrodeless discharge lamp according to claim 4, wherein the magnetic material having the lowest Curie temperature is disposed in the vicinity of the mercury amalgam. In this case, the magnetic permeability of the magnetic material is reduced first, and the function of the core is not fulfilled. Then, the heat generation due to the power loss from the magnetic material is suppressed, and the temperature rise of the mercury amalgam disposed near the magnetic material can be suppressed, whereby the mercury vapor pressure from the mercury amalgam can be reduced, Light output can be suppressed.
[0086]
The electrodeless discharge lamp according to claim 6 is the electrodeless discharge lamp according to any one of claims 1 to 5, wherein the lowest Curie temperature is a Curie temperature of 200 ° C or less. Heat resistance of about 200 ° C. can be used.
[0087]
The electrodeless discharge lamp according to claim 7 is the electrodeless discharge lamp according to any one of claims 1 to 5, wherein the magnetic material having the lowest Curie temperature contains manganese and zinc. At low temperatures when the light output of the electrode discharge lamp decreases, the light output of the electrodeless discharge lamp increases due to the increase in the magnetic permeability of the core, and at high temperatures when the light output increases, the light output decreases due to the decrease in the magnetic permeability of the core. And the light output can be made substantially constant from low to high temperatures.
[0088]
An electrodeless discharge lamp lighting device according to an eighth aspect of the present invention includes an electrodeless discharge lamp according to any one of the first to seventh aspects, a high-frequency power supply that supplies high-frequency power to an induction coil and has a variable supply power, A detection circuit for detecting the inductance of the coil is provided, and when the inductance falls below a predetermined value, control is performed to reduce the supplied power, so when the magnetic permeability of the core having the lowest Curie temperature decreases, By detecting a decrease in the inductance of the induction coil due to a decrease in the magnetic permeability, it is possible to reduce the power supplied to the electrodeless discharge lamp.
[0089]
According to a ninth aspect of the present invention, there is provided an electrodeless discharge lamp lighting device comprising: the electrodeless discharge lamp according to any one of the first to seventh aspects; A capacitive element connected in series with the coil; and a voltage detection circuit for detecting a voltage between both ends of the capacitive element, and when the detected voltage rises above a predetermined voltage, control is performed to reduce supply power. Therefore, when the electrodeless discharge lamp lighting device is abnormal, even if the voltage across the induction coil rises, the voltage that reflects the voltage across the induction coil is detected and the power supplied to the electrodeless discharge lamp is reduced. Can be done.
[0090]
According to the electrodeless discharge lamp lighting device of the tenth aspect, in the electrodeless discharge lamp lighting device of the eighth or ninth aspect, instead of performing the control of reducing the supply power, the control of intermittently supplying the power is performed. Since it is performed, the power supplied to the electrodeless discharge lamp can be suppressed when the inductance is reduced or the electrodeless discharge lamp lighting device is abnormal.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment.
FIG. 2 is a circuit diagram of the high-frequency power supply 12.
FIG. 3 is a cross-sectional view of a lighting device.
FIG. 4 is a diagram showing a path of a magnetic flux.
FIG. 5 is a diagram showing a general relationship between the temperature of the induction coil 4 and the inductance of the induction coil 4.
FIG. 6 is a diagram showing a relationship between the temperature of the induction coil 4 and the inductance of the induction coil 4 in the first embodiment.
FIG. 7 is a cross-sectional view illustrating a second embodiment.
FIG. 8 is a sectional view showing a conventional example.
FIG. 9 is a diagram showing a magnetic flux path in a conventional example.
[Explanation of symbols]
1 valve
2 cavity
3 core
3a, 3b Magnetic material constituting core
3c Magnetic material constituting core with the lowest Curie temperature
4 Induction coil
23 Mercury amalgam
12 High frequency power supply
C4 capacitor (capacitive element)
20 Voltage detection circuit (detection circuit)

Claims (11)

A substantially spherical valve having a cavity with an inverted U-shaped cross section in which a discharge gas is sealed, a columnar core made of a magnetic material disposed in the cavity, and high-frequency power supplied by being wound around the core An electrodeless discharge lamp comprising: an induction coil, wherein a plurality of magnetic materials having different Curie temperatures are continuously provided along a winding axis direction of the induction coil. The electrodeless discharge lamp according to claim 1, wherein the induction coil is not wound around the core having the lowest Curie temperature. The electrodeless discharge lamp according to claim 1 or 2, wherein the core having the lowest Curie temperature is disposed at a position farthest from the opening of the cavity. A substantially spherical valve having a cavity having an inverted U-shaped cross section in which a discharge gas is sealed and connected to each other, and an exhaust pipe formed between the cavities in the bulb and A mercury amalgam disposed in an exhaust pipe, a columnar core made of a magnetic material disposed in a hollow portion, and an induction coil wound around the core and supplied with high-frequency power, wherein the cores have different Curie temperatures An electrodeless discharge lamp, wherein a plurality of magnetic materials are continuously provided along a winding axis direction of an induction coil. The electrodeless discharge lamp according to claim 4, wherein the magnetic material having the lowest Curie temperature is disposed near the mercury amalgam. The electrodeless discharge lamp according to any one of claims 1 to 5, wherein the lowest Curie temperature is a Curie temperature of 200 ° C or less. The electrodeless discharge lamp according to any one of claims 1 to 5, wherein the magnetic material having the lowest Curie temperature includes manganese and zinc. An electrodeless discharge lamp according to any one of claims 1 to 7, a high-frequency power supply that supplies high-frequency power to the induction coil and has a variable supply power, and a detection circuit that detects inductance of the induction coil. An electrodeless discharge lamp lighting device, which performs control to reduce the supply power when the voltage falls below a predetermined value. An electrodeless discharge lamp according to any one of claims 1 to 7, a high-frequency power supply for supplying high-frequency power to the induction coil and variable power supply, a capacitive element connected in series with the induction coil, and a capacitor. A voltage detection circuit for detecting a voltage between both ends of the conductive element, wherein when the detected voltage rises above a predetermined voltage, control is performed to reduce supply power, thereby controlling the electrodeless discharge lamp lighting device. 10. The electrodeless discharge lamp lighting device according to claim 8, wherein control for supplying power intermittently is performed instead of performing control for reducing supply power. An illumination device comprising the electrodeless discharge lamp lighting device according to any one of claims 8 to 10, and lighting the electrodeless discharge lamp according to any one of claims 1 to 7.

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