JP2009238531A - Electrodeless discharge lamp lighting device, and illumination apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrodeless discharge lamp lighting device and an illumination apparatus, in which intensity of radiant noises can be suppressed even when ON-duty is low. <P>SOLUTION: Two types of operation frequencies f are used in dispersion even for lighting periods ON only and for extinction periods OFF only. Since the frequencies of radiant noises are dispersed, intensity of the radiant noises is suppressed. Furthermore, since the operation frequencies f are not changed in individual lighting period ON, even when the duration time of the lighting period ON is short, that is, when ON-duty is low, the operation frequencies f are dispersed, and the same effect is obtained as when the ON-duty is high. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrodeless discharge lamp lighting device and a lighting fixture using the electrodeless discharge lamp device.

  2. Description of the Related Art Conventionally, an electrodeless discharge lamp lighting device for lighting an electrodeless discharge lamp in which a discharge gas is sealed in a bulb made of a light-transmitting material such as glass has been provided. This type of electrodeless discharge lamp lighting device includes an induction coil disposed close to the electrodeless discharge lamp, and a power supply unit that supplies high-frequency power to the induction coil. An electromagnetic field is generated. When a discharge is generated in the bulb of the electrodeless discharge lamp by the high frequency electromagnetic field, the excited discharge gas emits ultraviolet rays. A fluorescent material is applied to the inner surface of the bulb of the electrodeless discharge lamp, and the ultraviolet light is converted into visible light by the fluorescent material, whereby the electrodeless discharge lamp emits light.

As this type of electrodeless discharge lamp lighting device, a dimming operation that lowers the light output is possible by alternately repeating a lighting period for turning on the electrodeless discharge lamp and a light-off period for turning off the electrodeless discharge lamp. There are some (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2004-247201

  Here, in a general discharge lamp lighting device using a hot cathode discharge lamp, it is only necessary to energize the discharge lamp, and it is not necessary to make an electromagnetic wave incident thereon. Therefore, a known technique for covering a circuit that generates radiation noise with a conductive material is used. It is relatively easy to suppress radiation noise. However, in the electrodeless discharge lamp lighting device, it is necessary to make the generated electromagnetic wave incident on the bulb, and since the bulb is a light emitting part, it is not possible to suppress radiation noise by means as in the case of the hot cathode discharge lamp described above. Is possible.

  Therefore, as shown in FIG. 14, by gradually decreasing the output frequency (hereinafter referred to as “operating frequency”) f of the power supply unit as time t elapses from the start to the end of the lighting period, It has been proposed to disperse the frequency of radiation noise and consequently suppress the intensity of radiation noise.

  However, in FIG. 14, the range that the operating frequency f can take and the range that the voltage Vcoil output to the induction coil can take are the lighting period that occupies the total of the duration of the lighting period and the duration of the extinguishing period. It is determined according to the ratio of duration (hereinafter referred to as “on duty”), and the above range is substantially constant in all lighting periods unless the on duty is changed. As the on-duty is lower, the range that the operating frequency f can take (that is, the fluctuation range of the operating frequency f) becomes narrower, and it becomes difficult to obtain the effect of suppressing the intensity of radiation noise.

  The present invention has been made in view of the above reasons, and an object thereof is to provide an electrodeless discharge lamp lighting device and a lighting fixture that can suppress the intensity of radiation noise even when the on-duty is low. It is in.

  According to the first aspect of the present invention, high-frequency electric power is supplied to an induction coil disposed in the vicinity of an electrodeless discharge lamp in which a discharge gas is sealed in a bulb made of a translucent material to generate a high-frequency electromagnetic field in the induction coil. An electrodeless discharge lamp lighting device that generates a discharge in a bulb by an electric field, and includes a power supply unit that supplies high-frequency power to an induction coil, and a control unit that controls a frequency of an output of the power supply unit. Dimming that alternately repeats the lighting period in which the electrodeless discharge lamp can be turned on and the light-out period in which the electrodeless discharge lamp cannot be turned on. The operation is possible, and the range that the frequency of the output of the power supply unit can take is periodically changed during the lighting period.

  According to the present invention, the intensity of radiation noise is suppressed by periodically changing the possible range of the output frequency of the power supply unit during the lighting period. In addition, unlike the case where the range that the output frequency of the power supply unit can take in each lighting period is common, the effect of suppressing the intensity of radiation noise can be obtained even if the on-duty is lowered.

  According to a second aspect of the present invention, in the first aspect of the invention, in each lighting period, the control unit gradually changes the frequency of the output of the power source unit from the start of the lighting period to the end of the lighting period. It is characterized by.

  According to this invention, compared with the case where the frequency of the output of a power supply part is not changed during a lighting period, the intensity | strength of radiation noise is further suppressed.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the control unit determines the effective value of the output voltage from the power source unit to the induction coil at the time when the electrodeless discharge lamp starts lighting in the next lighting period. The duration is shortened as the light extinction period becomes lower.

  According to the present invention, the extent to which the effective value of the output voltage to the induction coil is lowered and it takes time to turn on the electrodeless discharge lamp and the substantial lighting time is shortened is suppressed by shortening the immediately preceding extinguishing period. can do.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the control unit periodically changes the range of the output frequency of the power supply unit during the extinguishing period.

  According to this invention, the intensity of radiation noise during the extinguishing period can also be suppressed. Further, compared with a case where the range of the output frequency of the power supply unit can be changed only during the lighting period, the manufacturing cost can be reduced by realizing a simple circuit.

  Invention of Claim 5 is the electrodeless discharge lamp lighting device of any one of Claims 1-4, the electrodeless discharge lamp and electrodeless discharge lamp lighting device which are lighted by an electrodeless discharge lamp lighting device, And an instrument main body for holding each.

  According to the first aspect of the present invention, the intensity of radiation noise is suppressed by periodically changing the range of the output frequency of the power supply unit that can be taken during the lighting period. In addition, unlike the case where the range that the output frequency of the power supply unit can take in each lighting period is common, the effect of suppressing the intensity of radiation noise can be obtained even if the on-duty is lowered.

  According to the invention of claim 2, the control unit gradually changes the frequency of the output of the power supply unit from the start of the lighting period to the end of the lighting period in each lighting period. Compared with the case where the frequency of the output of the power supply unit is not changed, the intensity of radiation noise is further suppressed.

  According to the invention of claim 3, the control unit continues for a turn-off period in which the effective value of the output voltage from the power supply unit to the induction coil at the time when the electrodeless discharge lamp starts to turn on in the next turn-on period. Since the time is shortened, the effective value of the output voltage to the induction coil is lowered and it takes time to turn on the electrodeless discharge lamp. can do.

  According to the invention of claim 4, since the control unit periodically changes the range of the output frequency of the power supply unit during the extinguishing period, the intensity of radiation noise during the extinguishing period can also be suppressed. Further, compared with a case where the range of the output frequency of the power supply unit can be changed only during the lighting period, the manufacturing cost can be reduced by realizing a simple circuit.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  As shown in FIG. 2, the electrodeless discharge lamp lighting device 1 according to the present embodiment includes a DC power supply circuit 2 that converts AC power from an AC power supply AC into DC power of a voltage value VDC, and a DC output from the DC power supply circuit 2. Inverter circuit 3 as a power supply unit that converts power into high-frequency power of voltage value Vcoil, a control circuit 4 that controls inverter circuit 3, and induction coil 5 that generates a high-frequency electromagnetic field from the high-frequency power supplied from inverter circuit 3 With.

  The induction coil 5 is wound around a cylindrical coupler 50 as shown in FIG. In the example of FIG. 3, the electrodeless discharge lamp lighting device 1 is housed in a metal case 10 and is electrically connected to the induction coil 5 via the feeder 11.

  As shown in FIG. 4, the electrodeless discharge lamp 6 includes a hollow bulb 61 made of a transparent material such as glass and having a recess 60 on the outer surface, and a cylindrical shape made of synthetic resin. And a base 62 attached so as to surround the opening of 60. The coupler 50 is inserted into the recess 60 and is disposed in the vicinity of the induction coil 5. For example, a discharge gas containing an inert gas and metal vapor is sealed in the bulb 61. Further, a convex portion 61 a that is inserted into the coupler 50 protrudes from the bottom surface of the concave portion 60 of the bulb 61. Further, a protective film 62 and a phosphor film 63 are provided on the inner surface of the bulb 61. That is, when a discharge is generated in the bulb 61 by the high-frequency electromagnetic field generated by the induction coil 5, the generated ultraviolet light is converted into visible light in the phosphor film 63, whereby the electrodeless discharge lamp 6 emits light.

  The DC power supply circuit 2 includes a diode bridge DB that full-wave rectifies an AC current supplied from the AC power supply AC, and a series circuit of an inductor L1, a diode D1, and a smoothing capacitor C1 connected between output terminals of the diode bridge DB. The switching element Q1 connected between the connection point of the inductor L1 and the diode D1 and the output terminal on the low voltage side of the diode bridge DB, and switching with a duty ratio that keeps the voltage VDC across the smoothing capacitor C1 constant. This is a well-known step-up converter including a voltage control unit 21 that drives the element Q1 on and off.

  The inverter circuit 3 is in parallel with a series circuit of switching elements Q2 and Q3 connected between the output ends of the DC power supply circuit 2, that is, between both ends of the smoothing capacitor C1, and an inductor Ls connected between both ends of the low-side switching element Q3. A series circuit with a capacitor Cp, a series circuit with an induction coil 5 connected in parallel to a parallel capacitor Cp, and a drive unit 31 that alternately turns on and off the switching elements Q3 and Q4 are provided. The drive unit 31 turns on and off the switching elements Q2 and Q3 at a higher operating frequency f as the control current Ivp flowing out from the input terminal CON increases. Usually, the operating frequency f is in a range higher than the resonance frequency (hereinafter simply referred to as “resonance frequency”) of the resonance circuit formed by the inverter circuit 3 and the induction coil 5.

  The control circuit 4 receives the PWM oscillation circuit 40 that outputs the PWM signal Vpwm, and the PWM signal Vpwm from the PWM oscillation circuit 40. During the ON period of the PWM signal Vpwm, the control circuit 4 outputs the output voltage (hereinafter referred to as “coil voltage”). And a start sweep circuit 41 that gradually changes the frequency of the output of the inverter circuit 3 so as to gradually increase the effective value of Vcoil.

  The start sweep circuit 41 includes a resistor R1 having one end connected to the constant voltage source E1, a parallel circuit of a resistor R2 and one end connected to the other end of the resistor R1, and a capacitor C2, and a resistor connected to the other end of the parallel circuit. An operational amplifier OP1 having an inverting input terminal connected through R3 and an output terminal and an inverting input terminal connected through a feedback resistor R4, a resistor R5 having one end connected to the output terminal of the operational amplifier OP1, and a resistor R5 And a switching element Q4 connected between both ends of the capacitor C2 and driven on and off by the PWM signal Vpwm from the PWM oscillation circuit 40. And a series circuit of the resistor R6.

  The operation of the start sweep circuit 41 will be described. During the period when the PWM signal Vpwm is at the L level, the switching element Q4 is turned off, the capacitor C2 is charged by the voltage obtained by dividing the output of the constant voltage source E1 by the resistors R1 and R2, and the output voltage Vf of the operational amplifier OP1 is Rise gradually. Then, the effective value of the coil voltage Vcoil gradually increases as the control current Ivp decreases and the operating frequency f decreases and approaches the resonance frequency. Eventually, when the effective value of the coil voltage Vcoil becomes sufficiently high and discharge is started in the electrodeless discharge lamp 6, the electrodeless discharge lamp 6 starts to light. That is, the period in which the PWM signal Vpwm is at the L level is the lighting period in the claims.

  During the period when the PWM signal Vpwm is at the H level, the switching element Q4 is turned on, the charging to the capacitor C2 is stopped and the capacitor C2 is discharged, so that the output voltage Vf of the operational amplifier OP1 is lowered. Then, the effective value of the coil voltage Vcoil becomes low because the control current Ivp increases and the operating frequency f becomes high and moves away from the resonance frequency. The electrodeless discharge lamp 6 is turned off when the effective value of the coil voltage Vcoil falls below a level necessary for maintaining the lighting of the electrodeless discharge lamp 6. That is, the period during which the PWM signal Vpwm is at the H level is the extinguishing period in the claims.

  Furthermore, the control circuit 4 of the present embodiment includes a frequency dispersion circuit 42 for dispersing the operating frequency f. The frequency dispersion circuit 42 includes an oscillation circuit 42a that oscillates in synchronization with the PWM signal Vpwm, and a frequency control circuit 42b that generates an output that changes at a timing based on the output of the oscillation circuit 42a. The frequency control circuit 42b is connected to the input terminal CON of the driving unit 31 via a backflow prevention diode D3 with the anode directed to the input terminal CON of the driving unit 31, and the PWM is performed every two cycles of the PWM signal Vpwm. At the timing when the signal Vpwm rises (that is, the timing when the effective value of the coil voltage Vcoil falls), the output voltage in two steps of high and low is selectively switched and superimposed on the output of the start sweep circuit 41. When the on-duty of the PWM signal Vpwm is set to 100%, that is, when the extinguishing period is not provided, changes in the coil voltage Vcoil and the operating frequency f with respect to time t are as shown in FIG.

  That is, in the present embodiment, as shown in FIGS. 1 and 6, the period A in which the operating frequency f is lowered due to the high output voltage of the frequency dispersion circuit 42 and the PWM signal Vpwm is at the L level. During a certain lighting period ON, the average operating frequency f4 is the lowest and the effective value of the coil voltage Vcoil is the highest. The average operating frequency f1 is the highest in the period B in which the operating frequency f is increased due to the low output voltage of the frequency dispersion circuit 42 and in the period in which the PWM signal Vpwm is at the H level. As the value increases, the effective value of the coil voltage Vcoil becomes the lowest. Further, the average operating frequency f2 in the period A in which the operating frequency f is lowered by the frequency dispersion circuit 42 and the period in which the light-off period is OFF is the period B in which the operating frequency f is increased by the frequency dispersion circuit 42 and The average operating frequency f3 is higher than the average operating frequency f3 during the lighting period ON. The former operating frequency f2 is high enough to turn off the electrodeless discharge lamp 6, and the latter operating frequency f3 is turned on. It is as low as possible. In FIG. 1, the peak of the amplitude of the coil voltage Vcoil immediately after the start of the lighting period ON is due to a change in characteristics at the start of lighting of the electrodeless discharge lamp 6. In FIG. 6, a curve a indicates a characteristic when the electrodeless discharge lamp 6 is not lit, and a curve b indicates a characteristic when the electrodeless discharge lamp 6 is lit. That is, the control circuit 4 according to the present embodiment sets the operating frequency f during the lighting period ON and the operating frequency f during the OFF period OFF to a period that is four times the period of the PWM signal Vpwm (that is, one-fourth). Frequency).

  According to the above configuration, since the frequency distribution circuit 42 uses the operating frequency f in two different ways even between the lighting periods ON and between the extinguishing periods OFF, the frequency of the radiation noise is distributed. The intensity of radiation noise is suppressed.

  Also, when the duration of the lighting period ON is short, that is, when the on-duty is low, the operating frequency f is dispersed, and the same effect as when the on-duty is high can be obtained.

  Here, when the output of the frequency dispersion circuit 42 is switched at the timing when the effective value of the coil voltage Vcoil rises (that is, the timing at which the coil voltage Vcoil shifts from the extinguishing period to the lighting period), the electrode voltage is released due to the disturbance of the waveform of the coil voltage Vcoil. It can be considered that the lighting of the electric lamp 6 takes time and the substantial lighting time is shortened, so that the light output is lowered or electromagnetic noise is relatively increased. On the other hand, in the present embodiment, the output of the frequency dispersion circuit 42 is switched at the timing when the effective value of the coil voltage Vcoil falls (that is, the timing when the coil voltage Vcoil shifts from the lighting period to the extinguishing period). Compared with the case where the output of the frequency dispersion circuit 42 is switched at the rising timing, the influence of disturbance of the waveform of the coil voltage Vcoil, such as a decrease in optical output and generation of electromagnetic noise, is suppressed.

  In addition, when the operating frequency f is gradually increased during the lighting period as in the conventional example, the on-duty and the light output are such that the change width of the light output with respect to the change width of the on-duty becomes smaller as the on-duty is higher. The linearity is low in the correspondence relationship. On the other hand, in the above embodiment, since the operating frequency f is not changed except for the operation of the start sweep circuit 41 during the duration of each lighting period ON, the operating frequency is gradually increased during the lighting period as in the conventional example. As compared with the case of changing the output, the linearity is higher in the correspondence relationship between the change width of the on-duty of the PWM signal Vpwm and the light output of the electrodeless discharge lamp 6, so that the control of the light output by the on-duty becomes easier. Yes.

  Further, in the frequency dispersion circuit 42, instead of providing the oscillation circuit 42a, the output may be changed every time the frequency control circuit 42b detects the rising edge of the PWM signal Vpwm twice. If this configuration is adopted, the oscillation circuit 42a is not necessary, and the manufacturing cost can be reduced.

  In addition, although the periodic change of the operating frequency f by the frequency dispersion circuit 42 has two steps of high and low in the above embodiment, it may be three or more steps. In that case, the frequency of the radiation noise is higher. Since it is dispersed, the intensity of radiation noise can be further suppressed.

  Further, if the waveform of the output of the frequency control circuit 42b is appropriately changed, only the operating frequency f in the lighting period is periodically changed without changing the operating frequency f in the extinguishing period as shown in FIGS. In this case, unlike the example of FIG. 1 in which the operating frequency f is also varied during the extinguishing period, the effect of suppressing the intensity of radiation noise cannot be obtained during the extinguishing period. By keeping the operating frequency f during the period sufficiently high with respect to the resonance frequency, the power consumption during the extinguishing period can be reduced. In FIG. 7, the on-duty of the PWM signal Vpwm is 50%, and in FIG. 8, the on-duty of the PWM signal Vpwm is 75%. In the example of FIG. 8, since the on-duty is higher and the turn-off period is shorter than in the example of FIG. 7, the time from the start of the turn-on period until the electrodeless discharge lamp 6 is turned on and the coil voltage Vcoil decreases (hereinafter “ Called “re-ignition time”).

  Further, as shown in FIG. 9, a voltage generation circuit 43 that outputs a rectangular wave voltage interlocked with the PWM signal Vpwm is provided, and instead of using the constant voltage source E1 for charging the capacitor C2 of the start sweep circuit 41, the voltage The capacitor C2 may be charged by the output voltage of the generation circuit 43. Compared with the configuration of FIG. 1, the configuration of FIG. 9 includes a series circuit of a resistor R6 and a switching element Q4, a resistor R2 connected in parallel to the capacitor C2, and a resistor R1 that connects the capacitor C2 to the constant voltage source E1. Is not provided, one end of the capacitor C2 connected to the non-inverting input terminal of the operational amplifier OP1, a series circuit of a diode D4 whose anode is connected to the voltage generation circuit 43 and the charging side resistor R7, and a cathode The difference is that it is connected to the voltage generation circuit 43 via a parallel circuit of a series circuit of a diode D5 connected to the voltage generation circuit 43 and a discharge side resistor R8. That is, as an operation excluding the contribution of the frequency dispersion circuit 42, the maximum value of the voltage across the capacitor C2 due to the output voltage at the H level of the voltage generation circuit 43 during the period when the output of the voltage generation circuit 43 is at the H level. The operating frequency f gradually decreases with a time constant determined by the resistance value of the charging side resistor R7 and the capacitance value of the capacitor C2 up to the lowest value of the operating frequency f corresponding to the output frequency f. During the period of L level, the resistance value of the discharge side resistor R8 and the capacitor C2 are reduced to the maximum value of the operating frequency f according to the minimum value of the voltage across the capacitor C2 by the output voltage of the voltage generation circuit 43 at the L level. The operating frequency f gradually increases with a time constant determined by the capacitance value. The frequency dispersion circuit 42 generates an output synchronized with the PWM signal Vpwm, and is an output that gradually increases the operating frequency f during the lighting period, and the average values of the operating frequencies f are different from each other. Generate pattern output alternately. That is, the range that the operating frequency f can take during the lighting period is periodically changed. As a result, as shown in FIG. 10, the effective values of the operating frequency f and the coil voltage Vcoil are kept constant in each extinguishing period, and the lighting period is reached after the voltage across the capacitor C2 reaches the maximum value in each lighting period. Until the operation ends, the operating frequency f is gradually increased by the output of the frequency dispersion circuit 42, and the effective value of the coil voltage Vcoil gradually decreases. In addition, the range that the effective values of the operating frequency f and the coil voltage Vcoil can take is different between two consecutive lighting periods. That is, in the examples of FIGS. 9 and 10, the control circuit 4 has a range (upper limit value and lower limit value) that the operating frequency f can take during the lighting period with a cycle twice as long as the on / off cycle of the electrodeless discharge lamp 6. The operating frequency f at the end point (that is, the lower limit value of the operating frequency f is low) and the operating frequency f at the end point (that is, within the lighting period) are periodically changed. The upper limit value of the operating frequency f) is lowered. As a result, the intensity of the radiation noise is reduced as compared with a case where the operating frequency f is not changed during the lighting period and a case where the change range of the operating frequency f is common to all the lighting periods. If the operating frequency f is gradually increased during the lighting period as described above, the change width of the light output with respect to the change width of the on-duty becomes smaller as the on-duty is higher. Thus, as the change width of the operating frequency f within one lighting period is increased, it becomes more difficult to control the light output by the on-duty. Therefore, the change width of the operating frequency f within one lighting period is It is desirable not to make it too large. In the examples of FIGS. 9 and 10, the range that the operating frequency f can take between the two consecutive lighting periods is made different from each other, thereby periodically changing the range that the operating frequency f can take during the lighting period. Therefore, the change width of the operating frequency f as a whole in the plurality of lighting periods can be increased relative to the change width of the operating frequency f in one lighting period.

  By the way, in the lighting period in which the operating frequency f is high at the start and the effective value of the coil voltage Vcoil is low, it takes time (re-ignition time) to light the electrodeless discharge lamp 6, so that the electrodeless discharge lamp 6 is actually turned on. After that, the substantial lighting time from the start of the next turn-off period to the turn-off of the electrodeless discharge lamp 6 tends to be shortened. Therefore, as shown in FIG. 11, the control circuit 4 treats the lighting period and the extinguishing period for a plurality of periods (two periods in FIG. 11) as one control period, and the on-duty as a whole of the control period is PWM. The duration of each extinguishing period in the control period is made different from each other so as to match the on-duty of the signal Vpwm, and the next operating period has a high operating frequency f at the start (that is, the effective value of the coil voltage Vcoil is low). ) The duration may be shortened as the turn-off period is such that the re-ignition time tends to be longer. If this configuration is adopted, the extension of the re-ignition time due to the low effective value of the coil voltage Vcoil at the start is offset by the reduction of the re-ignition time due to the shortening of the previous extinguishing period. A substantial difference in lighting time due to a difference in operating frequency f between periods is suppressed. Since such a control circuit 4 can be realized by a well-known technique using, for example, a microcomputer, detailed illustration and description are omitted.

  Here, in each of the above examples, the PWM signal Vpwm generated by the PWM signal oscillation circuit 40 in the control circuit 4 is used. However, the present invention is not limited to this, and the PWM signal Vpwm input from the outside is used. May be used.

  Further, the control circuit 4 may stop the output of the inverter circuit 3 during the extinguishing period. Since such a control circuit 4 can be realized by a well-known technique, detailed illustration and description thereof are omitted.

  For example, as shown in FIGS. 12 and 13, the various electrodeless discharge lamp lighting devices 1 may be held together with an electrodeless discharge lamp 6 and a coupler 50 in an appropriately shaped fixture body 71 to form a lighting fixture 7. it can. Since such a fixture main body 71 and the lighting fixture 7 can be realized by a well-known technique, detailed illustration and description thereof will be omitted.

It is explanatory drawing which shows operation | movement of embodiment of this invention. It is a circuit block diagram which shows the same as the above. It is a perspective view which shows an example of the usage pattern same as the above. It is explanatory drawing which shows an example of the structure of an electrodeless discharge lamp. It is explanatory drawing which shows operation | movement when the on-duty of a PWM signal is 100% in the same as the above. It is explanatory drawing which shows the relationship between the operating frequency and coil voltage in the same as the above. It is explanatory drawing which shows operation | movement when the on-duty of a PWM signal is 50% of another form same as the above. It is explanatory drawing which shows operation | movement when the on-duty of a PWM signal is 75% of the form of FIG. It is a circuit block diagram which shows another form same as the above. It is explanatory drawing which shows the operation | movement of the form of FIG. It is explanatory drawing which shows operation | movement of another form same as the above. It is explanatory drawing which shows the example of the lighting fixture using the same as the above. It is explanatory drawing which shows another example of the lighting fixture using the same as the above. It is explanatory drawing which shows operation | movement of a prior art example.

Explanation of symbols

1 Electrodeless discharge lamp lighting device 3 Inverter circuit (Power supply in claims)
4 control circuit 7 lighting fixture 71 fixture body

Claims (5)

A high-frequency power is supplied to an induction coil that is disposed close to an electrodeless discharge lamp in which a discharge gas is sealed in a bulb made of a light-transmitting material to generate a high-frequency electromagnetic field in the induction coil, and this high-frequency electromagnetic field discharges the bulb. An electrodeless discharge lamp lighting device to be generated,
A power supply for supplying high frequency power to the induction coil;
A control unit that controls the output frequency of the power supply unit.The control unit sets the output frequency of the power supply unit within a range in which the electrodeless discharge lamp can be lit, and the output frequency of the power supply unit without electrode discharge. A dimming operation that alternately repeats the extinguishing period, in which the electric lamp cannot be lit, is possible, and the range that the output frequency of the power supply unit can take during the lighting period is periodically changed. An electrodeless discharge lamp lighting device.   2. The electrodeless discharge lamp lighting according to claim 1, wherein the control unit gradually changes the output frequency of the power supply unit from the start of the lighting period to the end of the lighting period in each lighting period. apparatus.   The control unit is characterized in that the duration is shortened in a turn-off period in which the effective value of the output voltage from the power supply unit to the induction coil at the time when the electrodeless discharge lamp starts to turn on in the next lighting period. The electrodeless discharge lamp lighting device according to claim 1 or 2.   The electrodeless discharge lamp lighting device according to any one of claims 1 to 3, wherein the control unit periodically changes a possible range of the output frequency of the power supply unit during the extinguishing period.   The electrode main body which hold | maintains the electrodeless discharge lamp lighting device of any one of Claims 1-4, and the electrodeless discharge lamp and electrodeless discharge lamp lighting device which are lighted by an electrodeless discharge lamp lighting device A lighting fixture comprising:

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