JP4206901B2 - Electrodeless discharge lamp lighting device - Google Patents

Description

  The present invention relates to an electrodeless discharge lamp lighting device that supplies, for example, high-frequency power to an induction coil and lights an electrodeless discharge lamp near the induction coil.

  Conventionally, various types of electrodeless discharge lamp lighting devices have been proposed and are commercially available. For example, as shown in FIG. 4, an electrodeless discharge lamp A, an induction coil 80, a high frequency circuit 81, a DC power supply circuit 82, and a control circuit 83 are provided, and a high frequency electromagnetic field is applied to the electrodeless discharge lamp A. There are electrodeless discharge lamp lighting devices that emit light.

  The induction coil 80 is disposed in the vicinity of the electrodeless discharge lamp A. The high frequency circuit 81 includes a resonance circuit 811 having a high Q and supplies high frequency power to the induction coil 80. The DC power supply circuit 82 converts the commercial power supply B into DC power and supplies the DC power to the high frequency circuit 81 and the control power supply 820. The control circuit 83 includes a drive unit 85 and a frequency sweep circuit 84 that varies the control current, and controls the high-frequency circuit 81 with a drive signal from the drive unit 85 so that the frequency of the high-frequency power increases as the control current increases.

  The electrodeless discharge lamp lighting device performs the following operation. For example, when the commercial power supply B is turned on and the control power supply 820 rises and DC power is supplied to the frequency sweep circuit 84, the rise detection unit C of the frequency sweep circuit 84 detects the rise of the power supply and detects the H signal (on Signal) and the switching element 840 is turned on. Accordingly, a desired low voltage is input to the input terminal 1 (positive input terminal) of the operational amplifier 841 and a low voltage is output according to the voltage value. Therefore, the frequency setting terminal of the driving unit 85 is connected via the diode 842. (Rfre) Pull out the control current from 850. Next, when the signal of the rising edge detection unit C becomes an L signal (off signal), the switching element 840 is turned off, and the capacitor 844 is gradually charged through the resistor 843, so that the voltage across the both ends rises. Along with this, the voltage of the input terminal 1 (positive input terminal) of the operational amplifier 841 rises, and the output voltage of the operational amplifier 841 rises according to the voltage value, and the drawing of the control current through the diode 842 is gradually suppressed. Therefore, the frequency of the high frequency power is changed from a high frequency to a low frequency so as to approach the resonance frequency of the resonance circuit 811, and a large current flows through the induction coil 80.

  In the electrodeless discharge lamp lighting device, the frequency of the high frequency power is varied so that a sufficient high frequency current (power) is generated in the induction coil 80 when the electrodeless discharge lamp A is started by turning on the power. Even if the frequency characteristics of the high-frequency circuit 81 deviate from the design value due to variations or the like, the electrodeless discharge lamp A can be turned on, and stress on circuit elements due to excessive voltage (power) can be prevented. .

  As another example, for example, as shown in FIG. 5, there is an electrodeless discharge lamp lighting device including a dimming circuit 86 and an intermittent oscillation circuit 87 in addition to the above configuration.

  The dimming circuit 86 inputs a dimming signal that is a duty signal, controls the control current so that the frequency of the high frequency power periodically changes by the dimming signal sweep circuit 860, and turns on the electrodeless discharge lamp A. The light is adjusted by repeatedly turning it off.

  The intermittent oscillation circuit 87 detects an abnormal voltage of the induction coil 80 when an abnormal load such as no load occurs, and at that time, for example, in order to oscillate high frequency power intermittently to protect the circuit, the switching element 810b. It is possible to restart the electrodeless discharge lamp A by outputting a duty signal that repeatedly shorts and opens between the gate and the source.

Patent Document 1 discloses the following electrodeless discharge lamp device. When the CPU is started, the oscillator is controlled to oscillate at a frequency different from the predetermined frequency at the time of lighting. This frequency passes through the waveform shaping circuit and the first power amplifier, and then the duplexer → second power amplifier ( 1) → matching circuit (1) → RF sensor (1) → applied to load via mixer. The CPU monitors the RF power detected by the RF sensor (1), and controls the oscillator to oscillate at a predetermined frequency when it is turned on when the predetermined RF power is reached. After passing through the power amplifier, it is applied to the load via the duplexer → second power amplifier (2) → matching circuit (2) → RF sensor (2) → mixer. Further, the CPU monitors the RF power detected by the RF sensor (2), and when it does not reach the predetermined RF power, determines that it is not lit and switches to the control at the start. In this way, it is possible to match the impedance at the time of starting and lighting.
JP 2001-102193 A (pages 4 to 6 and FIG. 1)

  However, as in the conventional electrodeless discharge lamp lighting device, at least one of the DC power supply circuit or the control power supply (hereinafter referred to as “power supply unit”) includes an electrolytic capacitor having a large capacity for voltage stabilization. Therefore, there is a problem that the following conditions occur.

  In the case of using a drive unit in which the drive signal stops at the same time as the power is turned off, if the power is turned on instantaneously after the power is turned off, the capacitor 844 shown in FIG. Later, the restart operation must be repeated. However, when the power is turned on instantaneously, the voltage of the electrolytic capacitor of the power supply unit is hardly decreased, and charging starts. Therefore, the rising detection unit C cannot detect the rising of the power supply. For example, the input terminal 1 (positive input terminal) of the operational amplifier 841 ) Is kept high, and the frequency of the high frequency power cannot be varied. Therefore, when the frequency characteristics of the high-frequency circuit deviate from the design value due to variations in circuit elements, a high-frequency current (power) sufficient for starting the electrodeless discharge lamp is not generated in the induction coil, and the electrodeless discharge lamp Cannot be turned on, or an excessive voltage (power) is generated in the circuit element, which may cause stress.

  The present invention has been made in view of the above points, and the object of the present invention is that the frequency characteristic of the high-frequency circuit deviates from the design value when the power is turned on instantaneously after being turned off. Another object of the present invention is to provide an electrodeless discharge lamp lighting device capable of reliably lighting an electrodeless discharge lamp and preventing stress of circuit elements due to an excessive voltage (power).

Invention of claim 1, said comprising an induction coil provided near the electrodeless discharge lamp, a DC power supply circuit for generating DC power, a plurality of switching elements and a resonance circuits for converting the DC power into high-frequency power while outputting the high-frequency power and the high frequency circuit for supplying to said induction coil, a pulse-shaped drive signal for varying the frequency of the on-off of the thus each switching element to the magnitude of the control current at power-on in each switching element, power supply A drive unit that stops output of the drive signal when turned off, and the drive unit is controlled by changing the magnitude of the control current to vary the frequency of the drive signal and gradually increase the on / off frequency of each switching frequency. or by decreasing gradually increasing the applied voltage of the induction coil and a frequency sweep circuit for starting the electrodeless discharge lamp, the frequency The EEPROM circuit is charged by the drive signal output from the drive unit and discharged when the output of the drive signal is stopped, a resistor connected in parallel to the capacitor to form a discharge path, and an increase in the charging voltage of the capacitor And an operational amplifier that varies the magnitude of the control current so that the voltage applied to the induction coil gradually increases .

  In this structure, the control current for the drive unit is varied by the drive signal from the drive unit, and the frequency of the high-frequency power changes, so the frequency characteristics of the high-frequency circuit deviate from the design value when the power is turned on and then turned on instantaneously. Even in such a state, the electrodeless discharge lamp can be reliably turned on, and the stress of the circuit element due to an excessive voltage (power) can be prevented.

  According to a second aspect of the present invention, in the first aspect of the present invention, a switching element that switches according to the drive signal is provided between the DC power supply circuit and the frequency sweep circuit. In this structure, the power of the drive signal may be as large as necessary for switching of the switching element, so that the power of the drive signal can be reduced.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a dimming circuit that varies the magnitude of the control current according to an input signal and an abnormal load are detected from the high-frequency circuit, and at the time of the detection. And an intermittent oscillation circuit that outputs an intermittent oscillation signal to the dimming circuit. In this structure, since the frequency of the high frequency power is changed by the input signal of the dimming circuit, the lighting of the electrodeless discharge lamp can be controlled. In addition, the intermittent oscillation protection function that changes the frequency of the high-frequency power based on the input of the intermittent oscillation signal to the dimming circuit when an abnormal load is detected works, thereby reducing the disadvantages of the electrodeless discharge lamp and the stress on the circuit elements. Can be prevented.

According to a fourth aspect of the present invention, in the invention according to the third aspect , the dimming circuit receives a duty signal and periodically varies the magnitude of the control current according to the duty signal. . In this structure, since the frequency of the high frequency power is periodically changed by the duty signal, it is possible to control the lighting of the electrodeless discharge lamp.

The invention according to claim 5 is the invention according to claim 3 or 4 , characterized in that the intermittent oscillation signal is a duty signal. In this structure, the electrodeless discharge lamp is started by periodically changing the frequency of the high-frequency power based on the intermittent oscillation signal that is a duty signal at the time of detecting an abnormal load. It is possible to prevent stress on the element.

  According to the present invention, when the power supply is turned on instantaneously after being turned off, the electrodeless discharge lamp can be reliably turned on even if the frequency characteristics of the high frequency circuit deviate from the design value. It is possible to prevent the stress of the circuit element due to a large voltage (power).

(Embodiment 1)
First, the basic configuration of the first embodiment will be described with reference to FIG.

  The electrodeless discharge lamp lighting device according to the first embodiment applies a high-frequency electromagnetic field and normally lights the electrodeless discharge lamp A. As shown in FIG. 1, the induction coil 1, the DC power supply circuit 2, And a high-frequency circuit 3 and a control circuit 4 including a drive unit 40 and a frequency sweep circuit 41.

  The induction coil 1 is provided in the vicinity of the electrodeless discharge lamp A, and generates a high frequency electromagnetic field when a high frequency current of, for example, several tens of kHz to several hundreds of MHz flows. Thereby, for example, a high-frequency plasma current is generated in the electrodeless discharge lamp A in which a discharge gas is sealed in a glass bulb, and ultraviolet light or visible light is generated in the electrodeless discharge lamp A.

  The DC power supply circuit 2 converts, for example, AC power of the commercial power supply B into DC power, and supplies the DC power to the high-frequency circuit 3 and a control power supply 20 described later. The DC power supply circuit 2 includes, for example, a diode bridge circuit (not shown) and a chopper circuit (not shown) for full-wave rectification of AC power in order from the input side. The chopper circuit (not shown) includes, for example, a step-up type, a step-down type, a polarity reversal type, and the like depending on a combination of a coil, a capacitor, a switching element, and the like. An electrolytic capacitor (not shown) having a large capacity is provided at the DC power output portion of the chopper circuit (not shown).

  The control power supply 20 converts the DC power from the DC power supply circuit 2 into DC power suitable for driving the drive unit 40 and the frequency sweep circuit 41, and supplies the DC power to the drive unit 40 and the frequency sweep circuit 41. Similarly to the DC power supply circuit 2, the control power supply 20 is provided with a chopper circuit (not shown) such as a step-up type, a step-down type, or a polarity inversion type. An electrolytic capacitor (not shown) having a large capacity is provided at the DC power output portion of the chopper circuit (not shown).

  The high frequency circuit 3 includes a conversion element 30 and a resonance circuit 31, converts DC power from the DC power supply circuit 2 into high frequency power, and supplies the high frequency power to the induction coil 1. The frequency of the high frequency power is, for example, several tens kHz to several hundreds MHz.

  The conversion element 30 includes, for example, two switching elements 30a and 30b. The switching elements 30a and 30b are, for example, transistors, which are driven by a drive signal from the drive unit 40 and turned on and off based on the drive signal. By turning off, DC power is converted into high frequency power.

  The resonance circuit 31 includes, for example, a coil 310 and three capacitors 311, 312, and 313, and is designed to increase Q and output a large high-frequency current (power) to the induction coil 1 in the vicinity of the resonance frequency. This is because, when there is no load, only the induction coil 1 becomes a load and generates a high-frequency current (power) sufficient for starting the electrodeless discharge lamp A.

  The control circuit 4 includes a drive unit 40 and a frequency sweep circuit 41, and operates with DC power from the control power supply 20. The control circuit 4 operates the drive unit 40 and the frequency sweep circuit 41 to gradually increase the voltage (power) generated in the induction coil 1 by changing the frequency of the high-frequency power when starting the electrodeless discharge lamp A. .

  The drive unit 40 has a function of changing the frequency of the high-frequency power by changing the switching state of the conversion element 30 according to the magnitude of the control current from the frequency sweep circuit 41 and the like, and driving the pulse with respect to the conversion element 30. Generate a signal. For example, the drive unit 40 outputs a drive signal Hout for driving the switching element 30a and a drive signal Lout for driving the switching element 30b. Further, the drive unit 40 includes a frequency setting terminal 400. When the control current from the frequency sweep circuit 41 to the frequency setting terminal 400 is large, for example, the frequency of the high frequency power is high, and when the frequency is small, the high frequency power is low. The drive signals Hout and Lout are changed so that the frequency becomes small.

  The frequency sweep circuit 41 is characterized in that the magnitude of the control current is varied by a drive signal (for example, Lout). The frequency sweep circuit 41 includes, for example, a capacitor 410, a resistor 411, and an operational amplifier 412. The capacitor 410 has a capacity of several tenths of that of an electrolytic capacitor (not shown) provided in the DC power supply circuit 2 or the control power supply 20. Further, a capacitor 413 and a resistor 414 are connected in parallel between the input terminal 2 (negative input terminal) side and the output side of the operational amplifier 412. A diode 415 through which current flows in the direction of the operational amplifier 412 is provided between the output side of the operational amplifier 412 and the frequency setting terminal 400 of the driving unit 40, and a resistor 416 is provided by branching from the frequency setting element 400 to the diode 415. Furthermore, the frequency sweep circuit 41 connects, for example, a diode 417 and a resistor 418 that flow in the direction of the capacitor 410 between the drive unit 40 and the capacitor 410 in series.

  In the operational amplifier 412, the voltage charged by the capacitor 410 is input to the input terminal 1 (positive input terminal), and the voltage of the induction coil 1 is input to the input terminal 2 (negative input terminal) from the high frequency circuit 3 via the resistor 419. A voltage based on the difference between the voltage at the input terminal 1 (positive input terminal) and the voltage at the input terminal 2 (negative input terminal) is output.

  The operating principle of the frequency sweep circuit 41 will be described. At the moment when the power is turned on, since the drive signal (for example, Lout) has not been output from the drive unit 40 until then, the capacitor 410 is not charged, and the input terminal 1 (positive input terminal) of the operational amplifier 412 is Low (low). Voltage). Therefore, the control current is extracted from the frequency setting terminal 400 of the drive unit 40 via the diode 415.

  When the drive unit 40 starts outputting a drive signal (for example, Lout) to drive the conversion element 30, the capacitor 410 is gradually charged via the diode 417. As the voltage of the capacitor 410 rises, the voltage at the input terminal 1 (positive input terminal) of the operational amplifier 412 rises, and the output voltage of the operational amplifier 412 rises according to the value. Thereby, drawing of the control current is gradually suppressed via the diode 415, and the output of the drive unit 40 shifts to a switching state in which the frequency of the high-frequency circuit 3 is brought close to the resonance frequency.

  When the power is turned off, the output of the drive signal (for example, Lout) is stopped, so that the capacitor 410 is instantaneously discharged through the resistor 411.

  Next, the operation of the first embodiment will be described with reference to FIG. When the commercial power supply B is turned off and turned on instantaneously, if the frequency characteristics of the high-frequency circuit deviate from the design value due to variations in circuit elements, the control current of the drive unit 40 is initially large and the frequency of the high-frequency power is high. The electrodeless discharge lamp does not light up because the resonance frequency of the resonance circuit 31 is too high. However, since the control current gradually decreases, the frequency of the high-frequency power decreases accordingly and approaches the resonance frequency. When the frequency of the high frequency power is close to the resonance frequency, the Q of the resonance circuit 31 is large, so that a sufficiently large high frequency current flows through the induction coil 1, a high frequency electromagnetic field is generated, and the electrodeless discharge lamp is turned on.

  As described above, according to the first embodiment, the control current for the drive unit 40 is varied by the drive signal (for example, Lout) from the drive unit 40, and the frequency of the high-frequency power is varied. Since the electrodeless discharge lamp A can be started at the same time, when the commercial power supply B is turned off immediately, even if the frequency characteristics of the high frequency circuit deviate from the design value, the frequency change of the high frequency power Can follow and the electrodeless discharge lamp A can be turned on. Thereby, the stress of the circuit element due to an excessive voltage (power) can be prevented.

(Embodiment 2)
First, the basic configuration of the second embodiment will be described with reference to FIG.

  The second embodiment is similar to the first embodiment in that the induction coil 1, the DC power supply circuit 2, the high frequency circuit 3, the driving unit 40, and the frequency sweep circuit 41 are provided, but the first embodiment is not. There are the following features. As shown in FIG. 2, a switching element 5 that is switched by a drive signal (for example, Lout) is provided between the DC power supply circuit 2 and the frequency sweep circuit 41 via the control power supply 20.

  The switching element 5 is, for example, a transistor, a driving signal (for example, Lout) is input to the gate, the source is connected to the control power supply 20, the drain is connected to the frequency sweep circuit 41, and the driving signal (for example, The current flows from the source to the drain by switching by Lout). Further, the frequency sweep circuit 41 is branched from the diode 417 and provided with a resistor 420.

  Next, the difference of the operation of the second embodiment from the first embodiment will be described. When the commercial power supply B is turned off and turned on instantaneously, a drive signal (for example, Lout) is input to the gate of the switching element 5. Along with this, a current intermittently flows from the control power supply 20 to the frequency sweep circuit 41 via the switching element 5. Thereby, the capacitor 410 is gradually charged and the voltage rises.

  When the commercial power source B is turned off, the drive signal (for example, Lout) stops, so that no current flows through the gate of the switching element 5 and no current flows between the source and drain of the switching element 5 at the same time.

  As described above, according to the second embodiment, since the switching element 5 is switched by the drive signal (for example, Lout), the power of the drive signal (for example, Lout) can be reduced. Further, since the electrodeless discharge lamp A can be started without being affected by the control power source 20 at the time of restart, the same effect as that of the first embodiment can be obtained.

(Embodiment 3)
First, the basic configuration of the third embodiment will be described with reference to FIG.

  The electrodeless discharge lamp lighting device of the third embodiment is for normally lighting the electrodeless discharge lamp A. As shown in FIG. 3, the induction coil 1, the DC power supply circuit 2, the high frequency circuit 3, and the drive The unit 40, the dimming circuit 6, and the intermittent oscillation circuit 7 are provided. Further, a frequency sweep circuit (not shown) is provided as in the first embodiment.

  The dimming circuit 6 includes, for example, a dimming signal sweep circuit 60, and periodically uses the dimming signal sweep circuit 60 to input high-frequency power using an input signal such as a duty signal input via the diode 61. The signal is converted so as to sweep the switching frequency of the frequency, and the magnitude of the control current to the frequency setting terminal 400 of the drive unit 40 is varied. Based on this control current, dimming is performed by repeatedly turning on and off the electrodeless discharge lamp A. However, the frequency switching period of the high-frequency power is set to a value that does not feel flicker, such as 120 Hz or more.

  The intermittent oscillation circuit 7 detects an abnormal load such as no load by inputting the voltage of the induction coil 1 from the high frequency circuit 3 via the resistor 70, and intermittently outputs a duty signal or the like via the diode 71 at the time of detection. An oscillation signal is output to the dimming circuit 6.

  First, the operation in the case where the commercial power source B according to the third embodiment is turned on immediately after being turned off is performed by changing the control current by a frequency sweep circuit (not shown) and performing the same operation as that in the first embodiment.

  Next, the operation in the case of dimming the electrodeless discharge lamp A of Embodiment 3 will be described with reference to FIG. The light control circuit 6 inputs a light control signal of a duty signal. The dimming circuit 6 varies the control current so that the frequency of the high frequency power periodically changes depending on on / off of the duty signal. Thereby, it is possible to perform light control by repeatedly turning on and off the electrodeless discharge lamp A.

  Furthermore, the intermittent oscillation protection function when detecting an abnormal load according to the third embodiment will be described. The dimmer circuit 6 inputs an intermittent oscillation signal of a duty signal from the intermittent oscillation circuit 7 when an abnormal load is detected. In the dimming circuit 6, for example, when the intermittent oscillation signal is on-duty, the control current is initially large and gradually decreases. Based on the change in the control current, the drive unit 40 drives the conversion element 30 to change the frequency of the high frequency power from a high frequency to a low frequency. The above operation is performed every time the on-duty is reached, and the start of the electrodeless discharge lamp A is repeated periodically.

  As described above, according to the third embodiment, since the frequency sweep circuit 41 similar to that of the first embodiment is provided, the same effect as that of the first embodiment can be obtained. Further, since the frequency of the high frequency power is varied by the dimming signal which is a duty signal, the electrodeless discharge lamp A can be dimmed. In addition, an intermittent oscillation protection function for inputting an intermittent oscillation signal, which is a duty signal, to the dimming circuit 6 when an abnormal load is detected and changing the frequency of the high-frequency power works, and the frequency of the high-frequency power is periodically changed to prevent electrodeless discharge. Since the start of the electric lamp A is repeated, the disadvantage of the electrodeless discharge lamp A and the stress on the circuit elements can be prevented.

  As a modification of the third embodiment, a configuration in which a frequency sweep circuit (not shown) is not provided may be employed. For example, when the dimming signal sweep circuit 60 is configured to vary the output voltage according to the ON period of the input signal, the dimming signal sweep circuit 60 is activated by the intermittent oscillation signal being turned on as described above in the initial operation of the intermittent oscillation circuit 7. Output voltage is swept from a low voltage to a high voltage, and the control current for the drive unit 40 is swept from a large current to a small current, so that the frequency of the high frequency power changes from a high frequency to a low frequency. The above operation is equivalent to the operation of the frequency sweep circuit (not shown) at the time of initial start in that the frequency of the high frequency power is changed from high frequency to low frequency. The electrodeless discharge lamp A can be started. As a result, when the power is turned off immediately after turning off the power, the electrodeless discharge lamp A can be reliably turned on even if the frequency characteristics of the high-frequency circuit 3 deviate from the design value. The stress of the circuit element due to the voltage (power) can be prevented. Further, since a frequency sweep circuit (not shown) is not required, the number of parts can be reduced. However, the present invention is not limited to this, and the same effect can be obtained even if the output voltage is varied according to the off period of the input signal.

It is a circuit diagram of the electrodeless discharge lamp lighting device of Embodiment 1 by the present invention. It is a circuit diagram of the electrodeless discharge lamp lighting device of Embodiment 2 by the present invention. It is a circuit diagram of the electrodeless discharge lamp lighting device of Embodiment 3 by the present invention. It is a circuit diagram of a conventional example. It is a circuit diagram of another conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Induction coil 2 DC power supply circuit 3 High frequency circuit 30 Conversion element 31 Resonance circuit 40 Drive part 41 Frequency sweep circuit 5 Switching element 6 Dimming circuit 7 Intermittent oscillation circuit A Electrodeless discharge lamp B Commercial power supply

Claims (5)

An induction coil provided near the electrodeless discharge lamp;
A DC power supply circuit for generating DC power ;
A high frequency circuit for supplying the high frequency power comprises a plurality of switching elements and a resonance circuits for converting the DC power into high frequency power to the induction coil,
While the output power of the on-time to the control current the frequency of on-off of the thus each switching element in magnitude to each of the switching elements a pulse-shaped drive signal for the variable, and a driving unit to stop the output of the drive signal when the power-off ,
The drive unit is controlled by varying the magnitude of the control current to vary the frequency of the drive signal and gradually increase or decrease the on / off frequency of each switching frequency to gradually increase the applied voltage of the induction coil. A frequency sweep circuit for starting the electrodeless discharge lamp ,
The frequency sweep circuit includes a capacitor that is charged by the drive signal output from the drive unit and is discharged when output of the drive signal is stopped, a resistor that is connected in parallel to the capacitor to form a discharge path, and a charge voltage of the capacitor An electrodeless discharge lamp lighting device comprising: an operational amplifier that varies the magnitude of the control current so that the voltage applied to the induction coil gradually increases as the voltage increases .   The electrodeless discharge lamp lighting device according to claim 1, further comprising a switching element that switches between the DC power supply circuit and the frequency sweep circuit according to the drive signal. A dimming circuit that varies the magnitude of the control current according to an input signal;
The electrodeless discharge lamp lighting device according to claim 1, further comprising: an intermittent oscillation circuit that detects an abnormal load from the high-frequency circuit and outputs an intermittent oscillation signal to the dimming circuit when the abnormal load is detected. 4. The electrodeless discharge lamp lighting device according to claim 3 , wherein the dimming circuit receives a duty signal and periodically varies the magnitude of the control current according to the duty signal . The electrodeless discharge lamp lighting device according to claim 3 or 4 , wherein the intermittent oscillation signal is a duty signal .

Images