JP2005063862A - Electrodeless discharge lamp lighting apparatus and lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrodeless discharge lamp lighting apparatus and a lighting device capable of applying a high voltage to an induction coil and thus improving the startup performance of an electrodeless discharge lamp even when variations arise in electronic components constituting a resonant circuit. <P>SOLUTION: A frequency control circuit 19 changes operating frequencies f of first and second switching elements Q2 and Q3. A voltage detecting circuit 9 detects a first operating frequency f1 at which the voltage that does not allow the electrodeless discharge lamp 5 to light up and that is applied to the induction coil 4 becomes maximum. After the first operating frequency f1 is detected, control is performed to shift the frequency from a second operating frequency f2 that is higher than the first operating frequency f1 to the first operating frequency f1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrodeless discharge lamp lighting device and an illumination device for lighting an electrodeless discharge lamp that emits light by applying a high-frequency electromagnetic field to a bulb in which a discharge gas is sealed.

  A conventional example of this type is disclosed in Japanese Patent Laid-Open No. 10-208894 (hereinafter referred to as Conventional Example 1). As shown in FIG. 10, the control circuit 6J1 gradually changes the output frequency from the frequency variable oscillation circuit OSC2J1 until the electrodeless discharge lamp 1J1 lights up. The output frequency is changed in the opposite direction, and the frequency is returned to the reference frequency f or the vicinity thereof. Thereafter, the switch SJ1 is switched, and a signal having a constant frequency from the frequency fixed oscillation circuit OSC1J1 is applied to the gates of the switching elements Q1J1 and Q2J1 of the amplifier circuit 5J1 via the transformer TJ1, and the electrodeless discharge lamp 1J1 is kept on. In this way, flickering or instability of the electrodeless discharge lamp during frequency switching is prevented.

Another conventional example is disclosed in Japanese Patent Application Laid-Open No. 2001-118695 (hereinafter referred to as Conventional Example 2). As shown in FIG. 11, this detects the current value at the moment when the input voltage and input current of the matching circuit 4J2 are in phase, or when the switching element 8bJ2 of the high frequency power supply circuit 3J2 is turned on or off. The oscillation frequency is controlled so that the detection signal becomes zero, so that the oscillation frequency is controlled so that the input power of the matching circuit 4J2 is constant at the vicinity of the resonance frequency of the load at the start and at the stable lighting. Thus, an electrodeless discharge lamp lighting device excellent in startability and power consumption stability is realized even when the load state varies due to variations in circuit element values.
JP-A-10-208894 JP 2001-118695 A

  In the conventional example 1, when the electrodeless discharge lamp 1J1 is started, the output frequency is gradually changed in the increasing direction of the oscillation frequency of the frequency variable oscillation circuit OSC2J1. However, when the actual resonance frequency deviates from the resonance frequency determined by calculation due to variations in the electronic components constituting the resonance circuit, the electrodeless discharge lamp 1J1 is started. Sometimes a sufficient starting voltage is not applied to the electrodeless discharge lamp 1J1. Therefore, when the ambient temperature of the electrodeless discharge lamp 1J1 is low, when the electrodeless discharge lamp 1J1 is to be started (hereinafter referred to as a low temperature start) or the electrodeless discharge lamp 1J1 is left in a dark place for a long time. In this case, when the electrodeless discharge lamp 1J1 is to be started (hereinafter referred to as a dark place start), the electrodeless discharge lamp 1J1 may be difficult to start.

  In the conventional example 2, the oscillation frequency is increased at the start of the electrodeless discharge lamp 1J2, and the resonance frequency is controlled to be a constant value. However, as in the conventional example 1, it is determined by calculation. When the actual resonance frequency deviates from the resonance frequency, a sufficient starting voltage may not be applied to the electrodeless discharge lamp 1J2 when starting the electrodeless discharge lamp 1J2. For this reason, even in the conventional example 2, the electrodeless discharge lamp 1J2 may be difficult to start at a low temperature start or a dark place start.

  The present invention has been made in view of the above problems, and the object of the present invention is to apply a high voltage to the induction coil even in the case where variations occur in each electronic component constituting the resonance circuit. It is possible to provide an electrodeless discharge lamp lighting device and a lighting device that can improve the startability of the electrodeless discharge lamp.

  In order to solve the above problem, in the present invention, the frequency control circuit changes the operating frequency of the first and second switching elements, and the voltage detection circuit applies a voltage that does not light the electrodeless discharge lamp to the induction coil. The first operating frequency when the maximum voltage is detected is detected, and after the first operating frequency is detected, the second operating frequency higher than the first operating frequency is shifted to the first operating frequency. Control is in progress.

  In the electrodeless discharge lamp lighting device of the present invention, even when the actual resonance frequency is deviated from the resonance frequency determined by calculation due to variations in each electronic component constituting the resonance circuit, the voltage detection circuit Since the first operating frequency that is higher than the first operating frequency is detected after the first operating frequency that is the actual resonance frequency is detected, when the electrodeless discharge lamp is started, A high voltage can always be applied to the induction coil, and the startability of the electrodeless discharge lamp can be improved.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a circuit diagram of the present embodiment, and FIG. 2 shows a cross-sectional view of an electrodeless discharge lamp 5. 3 shows a cross-sectional view of the lighting device, and FIG. 4 shows the relationship between the elapsed time t and the operating frequency f. Further, FIG. 5 shows a resonance curve, and FIG. 6 shows the frequency characteristics of the input impedance of a circuit composed of the inductor Ls and the capacitors Cs1, Cs2, and Cp. Furthermore, FIG. 7 shows the relationship between the elapsed time t and the operating frequency f of the application form of the present embodiment.

  Next, the configuration of each unit will be described.

  The AC power supply AC is a commercial AC power supply, and the voltage is, for example, 100V, 200V, or 240V.

  The rectifier circuit DB rectifies an alternating voltage from the alternating current power supply AC into a pulsating direct current voltage and outputs the pulsating direct current voltage. When the voltage of the AC power supply AC is 100 V, for example, a voltage doubler rectifier circuit may be used instead of the diode bridge. When the voltage doubler rectifier circuit is used, the voltage of the AC power supply AC can be regarded as substantially equal to 200 V, and the current flowing through the circuit connected after the voltage doubler rectifier circuit is about half that when using the diode bridge. As a result, the efficiency of the electrodeless discharge lamp lighting device can be increased.

  The chopper circuit 1a converts the pulsating DC voltage from the rectifier circuit DB into a desired DC voltage and outputs it, and includes a switching element Q1, a diode D1, an inductor L1, and a capacitor C1. The chopper circuit 1a converts the DC voltage from the rectifier circuit DB into a predetermined DC voltage E, and in this embodiment, a boost chopper circuit is used. Of course, the chopper circuit 1a may be a step-down chopper circuit or a step-up / step-down chopper circuit. In short, any circuit configuration may be used as long as it converts a DC voltage into another DC voltage and outputs it. The capacitor C1 smoothes the output voltage of the step-up chopper circuit 1a to obtain a DC voltage E, and is composed of, for example, an electrolytic capacitor.

  The AC power source AC, the rectifier circuit DB and the chopper circuit 1a constitute a DC power source 1, and the magnitude of the DC voltage E is controlled by controlling the switching element Q1.

  Although not shown here, a step-down chopper circuit may be further connected to the subsequent stage of the step-up chopper circuit 1a, and the direct-current power source 1 may be configured by the AC power supply AC, the rectifier circuit DB, the step-up chopper circuit 1a, and the step-down chopper circuit. When the step-down chopper circuit is connected to the subsequent stage of the step-up chopper circuit 1a, for example, a plurality of electrodeless discharge lamps having different rated power consumptions with a plurality of electrodeless discharge lamps having an AC power supply AC of 100V to 242V. This can be handled by a discharge lamp lighting device. That is, the step-up chopper circuit 1a makes the multi-power supply constant at the DC voltage E, and the step-down chopper circuit adjusts the power supplied to the electrodeless discharge lamp. This can be handled by an electrodeless discharge lamp lighting device.

The power conversion circuit 2 converts the DC voltage E from the capacitor C1 into a rectangular wave voltage by the on / off operation of the switching elements Q2 and Q3 which are the first and second switching elements, and the switching elements Q2 and Q3 are connected in series. It is constituted by a circuit. Switching elements Q2 and Q3 are composed of, for example, field effect transistors. The field effect transistor includes a diode in parallel between the source and the drain so that the drain of the field effect transistor is connected to the cathode of the built-in diode. Therefore, it is not necessary to attach a diode separately. Of course, instead of a field effect transistor, a combination of a transistor and a diode connected in antiparallel to the transistor may be used.
In the present embodiment, a so-called half-bridge type inverter circuit is used as the power conversion circuit 2. Of course, the power conversion circuit 2 may be a full bridge type or a push-pull type.

  The resonant circuit 3 applies a high voltage of about several kV to several tens of kV to the electrodeless discharge lamp 5 at the time of start-up by resonance operation, and turns on the electrodeless discharge lamp 5. The resonant circuit 3 includes an inductor Ls, The capacitors Cp, Cs1, and Cs2 are included. The resonance circuit 3 also functions as a so-called matching circuit that matches the impedance between the power conversion circuit 2 and the induction coil 4 and efficiently transmits high-frequency power from the power conversion circuit 2 to the induction coil 4.

  The electrodeless discharge lamp 5 is disposed close to the induction coil 4 and is lit by high-frequency power. Here, the electrodeless discharge lamp 5 will be described in more detail with reference to FIG.

  The electrodeless discharge lamp 5 includes a substantially spherical bulb 11 having a hollow section 15 having a concave cross-section, in which a discharge gas containing at least mercury and a rare gas is enclosed, and a discharge disposed in the hollow section 15. An induction coil 4 for supplying a high-frequency electromagnetic field to gas, a magnetic core around which the induction coil 4 is wound, a cylindrical core 13, and a member of a heat conductive material that is inside the core 13 and contacts the core 13 12.

  The bulb 11 has a substantially spherical shape, in which a discharge gas containing at least mercury and a rare gas is sealed, and a hollow portion having a bottom shape and a concave cross section at the lower end side of the bulb 11. 15 is provided. The material of the bulb 11 is a translucent material such as quartz glass, and the discharge gas is mercury, a rare gas, and a metal halide. Further, a phosphor 16 and a protective film 17 are applied to the inside of the bulb 11. The phosphor 16 converts ultraviolet rays emitted from mercury into visible light, and the phosphor 16 is made of calcium halophosphate, red phosphor (Y, Gd) BO3: Eu, green phosphor. Some CaPO4 and blue phosphor BaMgAll4O23: Eu are used. The protective film 17 improves the luminous flux maintenance factor of the bulb 11 by suppressing the reaction between mercury and quartz glass which is the material of the bulb 11. As the material of the protective film 17, fine particles such as alumina (Al2O3), silica (SiO2), titania (TiO2), ceria (CeO2), yttria (Y2O3), magnesia (MgO) are used. The protective film 17 is preferably formed thinner on the inner surface of the bulb 11 than the phosphor 16 because it is desirable that the normal bulb 11 has a higher transmittance.

The induction coil 4 supplies a high-frequency electromagnetic field oscillating at 13.56 MHz to the discharge gas inside the bulb 11, one of which is wound around the core 13 and the other is connected to the matching circuit 3. In this embodiment, a high frequency electromagnetic field of 13.56 MHz is supplied to the discharge gas. However, if the frequency is about 2.6 MHz to 15 MHz, which can reduce the adverse effects of radiation noise on other electrical devices, even at other frequencies. Good. For example, a frequency of several tens to several hundreds kHz that is normally used for lighting a fluorescent lamp may be used.
Here, the induction coil 4 is formed by winding a strip of copper or a copper alloy a predetermined number of times. The induction coil 4 is configured such that when the power conversion circuit 2 operates, a high-frequency current flows and a high-frequency electromagnetic field is generated around the induction coil 4. Next, the electrons in the bulb 11 are accelerated by the generated high-frequency electromagnetic field, collide with the atoms of the discharge gas, ionize the discharge gas, and generate new electrons. The electrons generated in this way receive energy by the high-frequency electromagnetic field generated around the induction coil 4 and collide with the discharge gas atoms to give energy. Atoms in the discharge plasma are ionized and excited. The excited atom emits light when returning to the ground state. This light emission is used as light energy.

  The member 12 has a substantially convex cross section, and is provided so that the core 13 is in contact with the outer side of the convex portion 12 a of the member 12.

  The core 13 has a substantially cylindrical shape in which the other end of the core 13 is fixed to the base 18 so that one end of the core 13 faces the center of the valve 11 inside the hollow portion 15. It is provided so that it may contact with the outer surface of the convex part 12a of the member 12. In the present embodiment, nickel zinc (NiZn) phylite, which is a soft magnetic material having a magnetic permeability of about 150, is used as the material of the core 13. Of course, any material including manganese zinc (Mn—Zn) ferrite and soft magnetic metal may be used. Alternatively, a soft magnetic metal alone may be used. Here, the soft magnetic material has a coercive force Hc in the bulk state of about 10 Oe or less.

  The base 18 is a bottomed substantially cylindrical body formed by aluminum die casting and having a top opening, and the above-described member 12 is erected and fixed to the bottom surface of the base 18 so as to face the center of the valve 11. ing. Further, a lid (not shown) is provided at the bottom.

  Here, reference numeral 21 denotes an electrodeless discharge lamp lighting device including a rectifier circuit DB, a chopper circuit 1a, and the like. In the present embodiment, the electrodeless discharge lamp lighting device 21 is housed in the base 18. Of course, the electrodeless discharge lamp lighting device 21 may be provided outside the base 18.

  The electrodeless discharge lamp 5 and the electrodeless discharge lamp lighting device 21 constitute an illumination device as shown in FIG. In this illuminating device, the bulb 11 is detachable from above the illuminating device, and a shield case 20 that absorbs radiation noise from the electrodeless discharge lamp 5 is covered, and a member 12 stands on the base 18. It is fixed. Of course, the illumination device for lighting the electrodeless discharge lamp 5 is not limited to such a shape.

  The frequency control circuit 19 controls the frequency of the switching elements Q2 and Q3 (hereinafter referred to as the operating frequency f) and the on-duty of the switching elements Q2 and Q3 and receives the detection signal from the voltage detection circuit 9 to The switching element Q4 is controlled when the electrode discharge lamp 5 is started. Moreover, the operating frequency f is lowered with the passage of time since the AC power supply AC is turned on, and the overvoltage to the induction coil 4 is increased. The frequency control circuit 19 outputs a reference clock signal for controlling the switching elements Q2 and Q3. By controlling the frequency or duty of the reference clock signal, the operating frequency f of the switching elements Q2 and Q3, or switching The on-duty of elements Q2 and Q3 is controlled. Then, this reference clock signal is input to the drive circuit 8. When the switching element Q4 is turned on, the frequency control circuit 19 receives the on signal and transmits an off signal to the switching element Q4 to turn off the switching element Q4.

  In this embodiment, a ST72G series microcomputer manufactured by ST Microelectronics is used as the frequency control circuit 19. When such a microcomputer is used, frequency and on-duty control can be easily performed by simply setting a program.

  The drive circuit 8 outputs a drive signal to the gates of the switching elements Q2 and Q3 in order to alternately turn on and off the switching elements Q2 and Q3 based on the reference clock signal from the frequency control circuit 19, and this embodiment In this embodiment, a high voltage half-bridge driver M63991 manufactured by Mitsubishi Electric Corporation is used. When the frequency of the reference clock signal changes, the frequency of the drive signal to the gates of the switching elements Q2 and Q3 changes, and the output of the electrodeless discharge lamp 5 can be changed.

  The chopper control circuit 7 controls the frequency of the switching element Q1 included in the chopper circuit 1a and controls the magnitude of the DC voltage E. When the DC voltage E is kept low, the power conversion circuit 2 operates. It is also possible to suppress the electrodeless discharge lamp 5 from being lit. As the chopper control circuit 7, an integrated circuit MC34261 manufactured by Motorola is used in this embodiment. This MC34261 has a capacitance value of a capacitor connected between the first pin (not shown) and the second pin (not shown), or a resistor connected to the first pin (not shown) after being divided from the DC voltage E. By simply changing the resistance value, the frequency of the input signal to the gate of the switching element Q1 output from the third pin (not shown) can be changed.

  The voltage detection circuit 9 detects the voltage across the capacitor Cs2. The voltage across the capacitor Cs2 is approximately proportional to the voltage V02 across the induction coil 4, and this voltage V02 is applied to the electrodeless discharge lamp 5.

  The voltage detection circuit 9 includes a resistor R1, diodes D2 and D3, and capacitors C2 to C4. The cathode of the diode D3 is connected to the cathode of the Zener diode ZD1, and the anode of the Zener diode ZD1 is connected to the switching element Q4.

  In this voltage detection circuit 9, when the voltage V02 across the voltage rises, the cathode voltage of the Zener diode ZD1 through the resistor R1, the diode D2, the capacitor C2, and the diode D3 exceeds the threshold voltage of the Zener diode ZD1, and the frequency control circuit 19 is turned on. Input the signal.

  Although not shown in FIG. 1, an IPD (intelligent power device) step-down circuit for supplying power to the chopper control circuit 7, the drive circuit 8, and the frequency control circuit 19 is provided in FIG. The IPD step-down circuit converts the DC voltage E into, for example, a DC voltage of 15V, and power is supplied to the chopper control circuit 7, the drive circuit 8, and the frequency control circuit 19 by this voltage. As such an IPD step-down circuit, the MIP series for switching power supply manufactured by Matsushita Electric Industrial Co., Ltd. is used.

  Next, the operation of the present embodiment will be described with reference to FIGS.

  When the AC power supply AC is turned on at t = t0, the DC power supply E is generated at both ends of the capacitor C1, and power is supplied to the IPD step-down circuit. Although a voltage of several tens of volts is applied to the chopper control circuit 7 by this IPD step-down circuit, the power conversion circuit 2 has not yet started operation at this point, and the both-end voltage V02 and the both-end voltage of the capacitor Cs2 are generated. Not done. Therefore, no charge is accumulated in the capacitor C4 via the resistor R1, the diode D2, the capacitor C2, and the diode D3, and the Zener diode ZD1 is not turned on. That is, the switching element Q4 is also turned off, and an off signal is input to the frequency control circuit 19 and the chopper control circuit 7. For this reason, the chopper control circuit 7 controls the switching element Q1, and the DC power source E has a voltage that does not light the electrodeless discharge lamp 5.

  Next, when the power conversion circuit 2 starts operating at t = t1, a resonance voltage is generated in the voltage V02 and the capacitor Cs2 due to the resonance operation of the resonance circuit 3. At this time, the DC power source E is kept low. (For example, several tens of volts), the electrodeless discharge lamp 5 is not lit yet. When the power conversion circuit 2 starts operating at t = t1 while the DC power source E is kept low, the frequency control circuit 19 operates the operating frequencies of the first and second switching elements Q2 and Q3 within the range shown in FIG. Will change. The change mode of the operating frequency at this time may be continuous or discrete. Then, the magnitude of the both-end voltage V02 due to the change in the operating frequency f is indirectly measured by the voltage of the capacitor C4, and the voltage of the capacitor C4 is monitored by the frequency control circuit 19. In this way, the operating frequency at which the voltage of the capacitor C4 is maximum, that is, the operating frequency at which the magnitude of the voltage V02 across the maximum is detected (hereinafter, this operating frequency is referred to as the first operating frequency f1) is detected.

  Theoretically, the first operating frequency f1 at which the magnitude of the both-end voltage V02 is the maximum is the resonance frequency that is uniquely determined by calculation from the constants of the inductor Ls, capacitors Cp, Cs1, and Cs2 that constitute the resonance circuit 3. It should match f0. However, in reality, the resonance frequency f0 and the first operating frequency f1 determined in the calculation may not coincide with each other due to variations of the components.

  Therefore, the first operating frequency f1 is found every time the AC power supply AC is turned on in consideration of variations of the components and changes in the constants of the components due to the ambient temperature. This first operating frequency f1 can be said to be a true resonance frequency in consideration of variations in each component and changes in the constants of each component due to the ambient temperature, and the operating frequency f in the vicinity of the first operating frequency f1. Then, the both-ends voltage V02 becomes very large.

  Then, during the period from t = t2 to t = t3, the operating frequency is continuously shifted from the second operating frequency f2 higher than the first operating frequency f1 to the first operating frequency f1. At the same time, the DC power source E is raised to, for example, 400V. Then, as the first operating frequency f1 is approached, the both-end voltage V02 becomes large enough for the electrodeless discharge lamp 5 to light, so that the startability of the electrodeless discharge lamp can be improved. In particular, it is extremely effective at low temperature start and dark start.

  Here, a setting condition of the second operating frequency f2 is considered. FIG. 6 shows the frequency characteristics of the input impedance of the circuit composed of the inductor Ls and the capacitors Cp, Cs1, and Cs2. | Z | represents the absolute value of the input impedance, and θ represents the phase angle of the input impedance. As can be seen from FIG. 6, there are three resonance frequencies at which θ = 0. Let the lowest resonance frequency be F0, the second highest resonance frequency, and f0 the highest resonance frequency. When a half-bridge type inverter circuit is used as the power conversion circuit 2 as in the present embodiment, when the impedance of the electrodeless discharge lamp 5 viewed from the power conversion circuit 2 becomes capacitive, the switching elements Q2 and Q3 are At the same time, a large current flows from the AC power supply AC, and an excessive stress may be applied to the components constituting the electrodeless discharge lamp lighting device.

  In order to avoid such a case, it is necessary to make the impedance of the electrodeless discharge lamp 5 viewed from the power conversion circuit 2 inductive (θ> 0) or resistive (θ = 0). In the case of the input impedance shown in FIG. 6, the frequency f at which the impedance becomes capacitive is F0 <f <f0. That is, when the second operating frequency f2> resonance frequency f0 is set, the impedance does not become capacitive.

  Here, a secondary winding may be provided in the inductor Ls, the number of turns of the secondary winding may be set as appropriate, and a voltage generated in the secondary winding may be directly input to the frequency control circuit 19. In this way, it is not necessary to provide the voltage detection circuit 9 that detects the high voltage generated at both ends of the induction coil 1b. Furthermore, the wiring length of the signal input to the frequency control circuit 19 can be shortened, and noise due to the wiring can be suppressed.

  As an application of the present embodiment, a timer circuit is separately provided, or a timer function is added to the frequency control circuit 19 having a microcomputer function by programming, and the second operating frequency f2 is periodically generated as shown in FIG. The operating frequency may be changed from 1 to the first operating frequency f1. Thus, when the both-ends voltage V02 is periodically changed, the startability of the electrodeless discharge lamp 5 may be further improved, which is effective at a low temperature start or a dark start. In addition, when such control is performed, compared to the case where the second operating frequency f2 is changed to the first operating frequency f1, and then the voltage V02 across the operating frequency f1 is continuously applied to the electrodeless discharge lamp 5, Since a high voltage does not continue to be applied to the electrodeless discharge lamp 5, it is possible to prevent excessive stress from being applied to the electronic components constituting the electrodeless discharge lamp lighting device.

  Furthermore, when the electrodeless discharge lamp 5 does not light even if the frequency change is repeated for a certain time, the electrodeless discharge lamp lighting device may be regarded as being in an abnormal state and the power conversion circuit 2 or the chopper circuit 1a may be stopped. . Furthermore, the frequency conversion frequency may be counted without using the timer circuit, and the power conversion circuit 2 or the chopper circuit 1a may be stopped when the frequency change frequency reaches a certain frequency.

  Furthermore, in the present embodiment, only the frequency control circuit 19 is made into a microcomputer, but of course, the chopper control circuit 7, the frequency control circuit 19 and the voltage detection circuit 9 may all be made into a microcomputer. Thus, if all the control circuits are made into microcomputers, the electrodeless discharge lamp lighting device can be made compact.

  Note that if the operating frequency is less than several tens of kHz, the loss in the induction coil 4 becomes very large and it becomes difficult to maintain lighting, which is not practical. When the operating frequency is several tens of MHz or more, not only the loss of the power conversion circuit 2 and the like increases, but also the copper loss due to the winding of the induction coil 4 becomes very large due to the skin effect, and the light emission efficiency is lowered. . Therefore, the operating frequency is preferably several tens of kHz to several tens of MHz. Further, depending on the type of the electrodeless discharge lamp 5, the operating frequency for outputting the rated power of the electrodeless discharge lamp 5 may coincide with the first operating frequency f1, but the first operating frequency f1 is set to 150 kHz. If set to the following, noise countermeasures in the Electrical Appliance and Material Safety Law may be facilitated, and the operating frequency when the electrodeless discharge lamp 5 is turned on may be set to 150 kHz or less in consideration of noise countermeasures. desirable.

  As described above, according to the present embodiment, even when the actual resonance frequency f1 deviates from the resonance frequency f0 determined by calculation due to variations in the electronic components and the like constituting the resonance circuit, the voltage detection circuit 9 Thus, after detecting the first operating frequency f1, which is the actual resonance frequency, the second operating frequency f2 higher than the first operating frequency f1 is shifted to the first operating frequency f1, so that the electrodeless discharge is performed. When the electric lamp 5 is started, a high voltage can always be applied to the induction coil 4 and the startability of the electrodeless discharge lamp 5 can be improved. This is particularly effective under conditions where the electrodeless discharge lamp 5 is difficult to start, such as when starting at a low temperature or when starting in a dark place.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. FIG. 8 shows the change over time of the resonance curve, and FIG. 9 shows the relationship between the elapsed time t and the operating frequency f. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The constants of the inductor Ls, capacitors Cp, Cs1, and Cs2 constituting the resonance circuit 3 change due to changes over time, and the resonance curve in the period (t2-t1) changes from C1A to C1B as shown in FIG. May end up. That is, the voltage V02 at both ends at the first operating frequency f1 may decrease. In such a case, after t = t2, even if the DC power source E is raised (about 300 to 500V), as shown in the resonance curve C2B of FIG. The electrodeless discharge lamp 5 may be difficult to start.

  Therefore, when the operating frequency is shifted from the second operating frequency f2 to the first operating frequency f1, the transition speed is changed as shown in FIG. That is, in the period (t2'-t2), the change speed of the operating frequency is decreased, and in the period (t3-t2 '), the change speed of the operating frequency is increased. When the operating frequency is controlled in this way to change the voltage V02 at both ends, the electrodeless discharge lamp 5 can be easily started even if the resonance curve changes to the resonance curve C2B due to changes over time.

  Of course, the change speed of the operating frequency may be increased during the period (t2'-t2), and the change speed of the operating frequency may be decreased during the period (t3-t2 '). In short, if the voltage V02 at both ends is given some sudden voltage change that is not monotonous, the startability is improved.

  Note that the operations and effects not particularly mentioned in the present embodiment are the same as those in the first embodiment.

1 is a circuit diagram showing a first embodiment. FIG. It is sectional drawing of an electrodeless discharge lamp. It is sectional drawing of an illuminating device. It is a figure which shows the relationship between the elapsed time t and the operating frequency f. It is a figure which shows a resonance curve. It is a figure which shows the frequency characteristic of input impedance. It is a figure which shows the relationship between the elapsed time t of this application form, and the operating frequency f. In 2nd Embodiment, it is a figure which shows the time-dependent change of the resonance curve. In 2nd Embodiment, it is a figure which shows the relationship between the elapsed time t and the operating frequency f. It is a circuit diagram which shows a 1st prior art example. It is a circuit diagram which shows a 2nd prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC power supply Q2 1st switching element Q3 2nd switching element 2 Power conversion circuit 3 Resonant circuit 4 Inductive coil 5 Electrodeless discharge lamp 9 Voltage detection circuit f1 1st operating frequency f2 2nd operating frequency 7 Control circuit 11 Valve 13 Core 12 Member 15 Cavity

Claims (5)

A DC power supply, a power conversion circuit having first and second switching elements that convert the DC power supply to high-frequency power and alternately turn on and off, a resonance circuit that resonates from the power conversion circuit with a rectangular wave voltage, and a resonance circuit An induction coil to which high-frequency power from is applied, an electrodeless discharge lamp that is disposed in proximity to the induction coil and is lit by high-frequency power, a frequency control circuit that controls the operating frequency of the first and second switching elements, and an induction coil A voltage detection circuit that detects a voltage applied to the first and second switching elements by the frequency control circuit, and the voltage detection circuit does not light the electrodeless discharge lamp. The first operating frequency when the voltage applied to the induction coil is maximized is detected, and after the first operating frequency is detected, the first operating frequency is detected. An electrodeless discharge lamp lighting device and performing control to shift to the first operating frequency from a higher second operating frequency than work frequency. 2. The electrodeless discharge lamp lighting device according to claim 1, further comprising a control circuit for controlling an output voltage of the DC power supply, and supplying a voltage at which the electrodeless discharge lamp does not light by lowering the output voltage. 3. The electrodeless discharge lamp lighting device according to claim 1, wherein the first operating frequency is greater than 150 kHz and not more than several tens of MHz, and the second operating frequency is greater than several tens of kHz and not more than 150 kHz. An electrodeless discharge lamp includes a substantially spherical bulb having a hollow portion with a concave cross section in which a discharge gas containing at least mercury and a rare gas is enclosed, and a high-frequency electromagnetic field disposed in the hollow portion. An induction coil to be supplied; a cylindrical core made of a magnetic material around which the induction coil is wound; and a member made of a heat conductive material that is inside the core and contacts the core. The electrodeless discharge lamp lighting device according to any one of claims 1 to 3. An illuminating device comprising the electrodeless discharge lamp lighting device according to any one of claims 1 to 4.

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