JPH10162977A - Discharge lamp lighting device and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which prevents phase advanced switching and reduces stress of a switching device or the like. SOLUTION: In a pre-heating or starting state before the lighting state of a fluorescent lamp FL, a pair of switching devices Q1, Q2 is controlled in the range of frequency of the maximum point f3 or more and parallel resonance frequency f2 or less. In the state that the fluorescent lamp FL is not lit, on-duty of a second switching device Q2 is made small with a constant frequency in the range of frequency of the maximum point f3 or more and parallel resonance frequency f2 or less, and thereby, the fluorescent lamp FL is pre-heated at relatively low voltage. After pre-heating of the fluorescent lamp FL was finished, on-duty of a second switching device Q2 is lengthened without varying frequency, output is slightly increased, and the fluorescent lamp FL is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device and an illuminating device in which fast switching is prevented.

[0002]

2. Description of the Related Art Hitherto, as a lighting apparatus of this kind, for example, a configuration described in Japanese Patent Application Laid-Open No. 8-98555 has been known.

In Japanese Patent Laid-Open Publication No. Hei 8-98555, a rectifier for performing non-smoothing rectification is connected to a commercial AC power supply, and the rectifier is alternately turned on at an output terminal of the rectifier at a frequency higher than the output frequency of the commercial AC power supply. A pair of switching devices connected in series to be turned off are connected, and a relatively large-capacity first capacitor and a second capacitor for resonance are connected, and between the pair of switching devices and the first capacitor. An inductor is connected in between, a discharge lamp is connected to the output side of the inductor, and a pair of switching devices are turned on and off at a substantially constant frequency by switching control means,
The input power factor is improved to reduce input distortion.

[0004]

However, in the case of the configuration described in Japanese Patent Application Laid-Open No. Hei 8-98555, a pair of switching devices are controlled at a frequency corresponding to a state where the discharge lamp is normally lit. Therefore, when the discharge lamp is lightly loaded, for example, at the time of preheating, at the time of starting, at the end of life, or in a state where the discharge lamp is removed, phase switching is performed, which may cause a large stress to a pair of switching devices. Have.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a discharge lamp lighting device and an illuminating device in which phase switching is prevented to reduce stress of a switching device and the like.

[0006]

According to a first aspect of the present invention, there is provided a discharge lamp lighting device comprising: a rectifier for rectifying an output voltage of an AC power supply to output a non-smooth DC voltage; A pair of switching devices that are alternately turned on and off at a frequency higher than the output frequency of the rectifier;
A series circuit of a first capacitor and an inductor provided between both terminals of one of the switching devices and smoothing the output frequency of the rectifier; and cooperating with the inductor according to ON / OFF of the pair of switching devices. An output circuit for lighting a discharge lamp based on resonance of the inductor and the second capacitor; an output circuit and a load circuit connected to the output circuit before the discharge lamp is turned on Switching control means for controlling the pair of switching devices at a frequency lower than either the series resonance frequency or the parallel resonance frequency. The first capacitor smoothes the unsmoothed DC voltage of the rectifier, and the second capacitor and the inductor turn on and off the pair of switching devices.
A resonance voltage is generated in response to the turning off, and the resonance voltage lifts a valley of the non-smooth DC voltage and smoothes the envelope of the high-frequency output voltage. The resonance voltage causes the voltage across the first capacitor and the second capacitor, or the voltage across the first capacitor, to be lower than the non-smoothing DC voltage of the rectifier during one cycle of switching of the pair of switching devices. Therefore, during one cycle of switching of the pair of switching devices, a charging current flows from the AC power supply to the first capacitor, and the charging current causes the input current to flow even during a period in which the peak value of the rectified non-smoothed DC voltage is low. While securing the input power factor, the input current is reduced to reduce the harmonics of the input current. Further, when the pair of switching devices are turned on and off at a substantially constant frequency by the switching control means, the ratio of the on period of the pair of switching devices can be changed, and the on period is changed,
When the amplitude of the resonance voltage changes and the ON period of one of the switching devices is relatively increased, the current value flowing through the inductor before the resonance operation increases, the amplitude of the resonance voltage increases, and the output voltage is varied. . Further, the switching control means controls the pair of switching devices at a frequency lower than any of the series resonance frequency and the parallel resonance frequency of the output circuit and the load circuit connected to the output circuit before the discharge lamp is turned on. Therefore, the load does not become capacitive and the phase switching is not performed, so that a large stress is not applied to the pair of switching devices.

According to a second aspect of the present invention, in the discharge lamp lighting apparatus according to the first aspect, the switching control means controls the on-duty by changing the on-duty at a constant frequency before the discharge lamp is turned on. The output is controlled in each state before the discharge lamp is turned on, for example, at the time of preheating, at the time of starting, or the like, without leading to phase switching.

According to a third aspect of the present invention, in the discharge lamp lighting device according to the first or second aspect, after the discharge lamp is turned on, the switching control means controls the frequency to a frequency near the parallel resonance frequency. The control is performed by varying the frequency. Even after the discharge lamp is turned on and the load is changed, the control is performed without leading to the fast switching.

According to a fourth aspect of the present invention, there is provided a discharge lamp lighting device, comprising: a rectifier for rectifying an output voltage of an AC power supply to output a non-smooth DC voltage; A pair of switching devices that are turned on and off in a forward polarity from on and off in a reverse polarity, and are turned on and off alternately at a frequency higher than the output frequency of the rectifier device;
A series circuit of a first capacitor and an inductor provided between both terminals of one of the switching devices and smoothing the output frequency of the rectifier; and cooperating with the inductor according to ON / OFF of the pair of switching devices. A second capacitor that resonates with the output; an output circuit that turns on the discharge lamp based on the resonance of the inductor and the second capacitor; and a current that flows through one of the switching devices located on the side that charges the first capacitor has an opposite polarity. Turn on in the state of
A switching control means for turning the current to a forward polarity, again to a reverse polarity, and then to a forward polarity, and then turning off. Then, the first capacitor smoothes the unsmoothed DC voltage of the rectifier, and the second capacitor and the inductor generate a resonance voltage in accordance with ON / OFF of the pair of switching devices. The valley of the voltage is raised, and the envelope of the high-frequency output voltage is smoothed. The resonance voltage causes the voltage across the first capacitor and the second capacitor, or the voltage across the first capacitor, to be lower than the non-smoothing DC voltage of the rectifier during one cycle of switching of the pair of switching devices. Therefore, during one cycle of switching of the pair of switching devices, a charging current flows from the AC power supply to the first capacitor, and the charging current causes the input current to flow even during a period in which the peak value of the rectified non-smoothed DC voltage is low. While securing the input power factor, the input current is reduced to reduce the harmonics of the input current. In addition, the switching control means turns on and off the pair of switching devices at a substantially constant frequency, and can change the ratio of the on-period of the pair of switching devices. When the on-period is changed, the amplitude of the resonance voltage changes. However, if the ON period of one switching device is relatively increased, the value of the current flowing through the inductor before the resonance operation increases, the amplitude of the resonance voltage increases, and the output voltage is varied. Further, the switching control means turns on the current flowing through one of the switching devices located on the side where the first capacitor is charged, in a state of reverse polarity, and this current turns to forward polarity, turns to reverse polarity again, and turns to forward polarity. Since it is turned off after turning to, the phase switching does not occur, so that a large stress is not applied to a pair of switching devices.

According to a fifth aspect of the present invention, there is provided a discharge lamp lighting device which rectifies an output voltage of an AC power supply and outputs a non-smooth DC voltage; A pair of switching devices that are turned on and off in a forward polarity from on and off in a reverse polarity, and are turned on and off alternately at a frequency higher than the output frequency of the rectifier device;
A series circuit of a first capacitor and an inductor provided between both terminals of one of the switching devices and smoothing the output frequency of the rectifier; and cooperating with the inductor according to ON / OFF of the pair of switching devices. A second capacitor that resonates with the output; an output circuit that turns on the discharge lamp based on the resonance of the inductor and the second capacitor; and a current that flows through one of the switching devices located on the side that charges the first capacitor has an opposite polarity. Turn on in the state of
When n is a natural number, a switching control unit that turns off after this current has turned to the (n + 1) th forward polarity is provided. The first capacitor smoothes the unsmoothed DC voltage of the rectifier, and the second capacitor and the inductor turn on and off the pair of switching devices.
A resonance voltage is generated in response to the turning off, and the resonance voltage lifts a valley of the non-smooth DC voltage and smoothes the envelope of the high-frequency output voltage. The resonance voltage causes the voltage across the first capacitor and the second capacitor, or the voltage across the first capacitor, to be lower than the non-smoothing DC voltage of the rectifier during one cycle of switching of the pair of switching devices. Therefore, during one cycle of switching of the pair of switching devices, a charging current flows from the AC power supply to the first capacitor, and the charging current causes the input current to flow even during a period in which the peak value of the rectified non-smoothed DC voltage is low. While securing the input power factor, the input current is reduced to reduce the harmonics of the input current. Further, when the pair of switching devices are turned on and off at a substantially constant frequency by the switching control means, the ratio of the on period of the pair of switching devices can be changed, and the on period is changed,
When the amplitude of the resonance voltage changes and the ON period of one of the switching devices is relatively increased, the current value flowing through the inductor before the resonance operation increases, the amplitude of the resonance voltage increases, and the output voltage is varied. . Further, the switching control means turns on the current flowing through the one switching device located on the side where the first capacitor is charged in a state of reverse polarity, and when n is a natural number, this current becomes (n +
1) Since the switch is turned off after the first switching to the forward polarity, the phase switching does not occur, so that a large stress is not applied to a pair of switching devices.

According to a sixth aspect of the present invention, there is provided a discharge lamp lighting device which rectifies an output voltage of an AC power supply and outputs a non-smooth DC voltage; and a rectifier which is provided in series between output terminals of the rectifier. A pair of switching devices that are turned on and off alternately at a frequency higher than the output frequency of the first switching device; a first large-capacity switching device provided in parallel with one of the switching devices.
And an inductor interposed between the pair of switching devices and between the first capacitor; and a capacitance larger than the first capacitor forming a resonance circuit with the other switching device and the inductor during the ON period of the other switching device. A second capacitor having a small value; an output circuit for lighting a discharge lamp based on resonance of the inductor and the second capacitor; and a current flowing through one of the switching devices located on the side where the first capacitor is charged has an opposite polarity. In this state, when n is a natural number, this current is (n
+1) switching control means for turning off after turning to the forward polarity for the first time. Then, the first capacitor smoothes the unsmoothed DC voltage of the rectifier, and the second capacitor and the inductor generate a resonance voltage in accordance with ON / OFF of the pair of switching devices. The valley of the voltage is raised, and the envelope of the high-frequency output voltage is smoothed. Depending on the resonance voltage, the voltage across the first capacitor and the second capacitor, or
The voltage across the first capacitor is made lower than the unsmoothed DC voltage of the rectifier during one cycle of switching of the pair of switching devices. Therefore, during one cycle of switching of the pair of switching devices, a charging current flows from the AC power supply to the first capacitor, and the charging current causes the input current to flow even during a period in which the peak value of the rectified non-smoothed DC voltage is low. While securing the input power factor, the input current is reduced to reduce the harmonics of the input current. In addition, the switching control means turns on and off the pair of switching devices at a substantially constant frequency, and can change the ratio of the on-period of the pair of switching devices. When the on-period is changed, the amplitude of the resonance voltage changes. However, if the ON period of one switching device is relatively increased, the value of the current flowing through the inductor before the resonance operation increases, the amplitude of the resonance voltage increases, and the output voltage is varied. further,
The switching control means turns on the current flowing through one of the switching devices located on the side where the first capacitor is charged, in a state of reverse polarity, and when n is a natural number, this current becomes the (n + 1) th forward polarity. Since it turns off after turning,
Since the phase switching does not occur, a large stress is not applied to the pair of switching devices.

According to a seventh aspect of the present invention, in the discharge lamp lighting device according to any one of the fourth to sixth aspects, the operation of the switching control means is an operation before the discharge lamp is turned on. In addition, even in a light load state before the discharge lamp is turned on, the phase switching does not occur, so that a large stress is not applied to the pair of switching devices.

The discharge lamp lighting device according to claim 8 is the discharge lamp lighting device according to any one of claims 4 to 7, wherein the switching control means operates at least at the end of the life of the discharge lamp and at the time of removal of the discharge lamp. Since the operation is performed in one of the states, the phase switching is not performed even at the end of the life of the discharge lamp and when the discharge lamp is removed, so that a large stress is not applied to the pair of switching devices.

According to a ninth aspect of the present invention, there is provided an illuminating device comprising: the discharge lamp lighting device according to any one of the first to eighth aspects; and a fixture main body including the discharge lamp lighting device and having a discharge lamp mounted thereon. Has the effect of

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a lighting device according to an embodiment of the present invention.

FIG. 1 is a circuit diagram showing a discharge lamp lighting device, FIG. 2 is a perspective view showing the appearance of the lighting device, FIG. 3 is a graph showing the relationship between the oscillation frequency and the output voltage, and FIG. FIG. 5 is a waveform diagram of a driving voltage for driving a pair of switching devices.

As shown in FIG. 2, reference numeral 1 denotes an apparatus main body, and the apparatus main body 1 is a so-called inverted Fuji type having a reflector 2 formed on a surface thereof and attached to a ceiling surface (not shown) or the like. Further, two pairs of lamp sockets 3 are arranged in the longitudinal direction at both ends of the reflection plate 2 of the instrument body 1, respectively. Fluorescent lamps FL as discharge lamps are mounted on these lamp sockets 3, respectively. The discharge lamp lighting device 11 shown in FIG.
Is stored.

In the discharge lamp lighting device 11, as shown in FIG. 1, a filter circuit 12 having a choke coil L1 and a capacitor C1 is connected to a commercial AC power supply e. The input terminal of the configured full-wave rectifier 13 of the diode bridge is connected.

A first switching device Q1 as one switching device and a second switching device Q2 as the other switching device are connected in series between output terminals of the full-wave rectifier 13. Each of the first switching device Q1 and the second switching device Q2 has a field-effect transistor using a parasitic diode for reverse current flow.

Further, between the output terminals of the full-wave rectifier 13, a first capacitor C2 for charging, which has a relatively large capacity, corresponds to the first switching device Q1 and the second switching device Q2, respectively. And the first capacitor C2
A second capacitor C3 for resonance having a much smaller capacity is connected in series.

The connection point between the first switching device Q1 and the second switching device Q2 and the connection point between the first capacitor C2 and the second capacitor C3 are shared with the second capacitor C3. The primary winding Tr1a of a leakage type insulation transformer Tr1 as an inductor which operates and oscillates is connected to the secondary winding Tr1b as an output circuit of the insulation transformer Tr1, and the filament FLa and the filament FLb of the fluorescent lamp FL are connected to the primary winding Tr1b of the insulation transformer Tr1. One end is connected and the filament FLa
A starting capacitor C4 is connected between the other end of the filament FLb. The insulation transformer Tr1 is
It also has the effect of the current limiting impedance of the fluorescent lamp FL.

The first switching device Q1 and the second switching device Q2 are controlled by switching control means 14, respectively. When controlling the first switching device Q1 and the second switching device Q2, a period is provided in which one is turned off from on and the other is substantially turned off when the other is turned on from off. It is not necessary. The switching control means 14 has an oscillator 15 for changing the frequency and the on-duty and a drive circuit 16 for driving. The switching control means 14 controls the frequency by controlling the frequency and the PWM by changing the on-duty. Control.

A starting detection circuit (not shown) detects the preheating, starting and lighting state of the fluorescent lamp FL, and the starting detection circuit includes a circuit for directly detecting the light of the fluorescent lamp FL, detecting a current or detecting a voltage, Alternatively, an arbitrary device such as a timer circuit can be used.

Further, as for the switching current, when detecting the current of the first switching device Q1, a resistor is connected in series to the first switching device Q1, and the current is converted into a voltage by this resistor. To detect the current value
When the current of the switching Q2 is detected, the primary winding of the current transformer is connected in series to the second switching device Q2, and the current value of the secondary winding of the current transformer is detected. The current value of the second switching device Q2 is detected.

Next, the operation of the above embodiment will be described.

First, the voltage of the commercial AC power supply e is input to the full-wave rectifier 13 through the filter circuit 12, and the full-wave rectifier 13 performs full-wave rectification. On the other hand, the first switching device
Q1 and the second switching device Q2 are oscillated at a frequency higher than the power supply frequency of the commercial AC power supply e, several kHz or more, preferably 20 kHz or more which is higher than the audible frequency, and a high-frequency AC voltage is applied to the secondary winding Tr1b of the insulating transformer Tr1. And the fluorescent lamp FL is turned on.

A resonance voltage is generated by the second capacitor C3 and the isolation transformer Tr1, and the resonance voltage
Even during a period in which the peak value of the voltage rectified by the full-wave rectifier 13 is low, a current flows from the commercial AC power supply e to achieve a high power factor and low distortion.

More specifically, first, when the first capacitor C2 is charged, the first switching device
When Q1 is closed, the first capacitor C2, the isolation transformer Tr
1 forms a closed circuit of the primary winding Tr1a, the first switching device Q1 and the first capacitor C2,
C2 discharges.

Next, since the first switching device Q1 is turned off and the second switching device Q2 can conduct reverse current, the primary winding Tr1a of the insulating transformer Tr1, the second switching device Q2, and the second Capacitor C3 and isolation transformer Tr
1 is closed, and the isolation transformer Tr1
In addition, a series resonance occurs in the second capacitor C3, and a resonance current flows. Then, a resonance voltage appears in the second capacitor C3 and the primary winding Tr1a of the insulating transformer Tr1, and the resonance voltage is determined by the magnitude of the current that is cut off when the first switching device Q1 is turned off, It also appears at the voltage of the full-wave rectifier 13 equal to the sum of the voltage of the second capacitor C3 and the voltage of the first capacitor C2.

When the second switching device Q2 is turned on, the second capacitor C3 and the second switching device Q
2. A closed circuit is formed between the primary winding Tr1a of the insulating transformer Tr1 and the second capacitor C3, the polarity of the resonance current is inverted, and a resonance current in the opposite direction flows, thereby generating a resonance voltage. In any case, the resonance voltage increases the pulsating voltage.

The primary winding Tr1a of the insulating transformer Tr1
When the resonance voltage due to the second capacitor C3 decreases, the voltage across the second capacitor C3 and the first capacitor C2 also decreases, so that the primary voltage of the full-wave rectifier 13, the second switching device Q2, and the isolation transformer Tr1 is reduced. Winding Tr1a, 1st
And the full-wave rectifier 13 is closed, and the first capacitor C2 is charged.

Further, since the second switching device Q2 is turned off and the reverse current of the first switching device Q1 can flow, the primary winding Tr1a of the insulating transformer Tr1, the first capacitor C2, the first switching device Device Q1 and isolation transformer Tr
1 is closed, and the isolation transformer Tr1
A current flows through the primary winding Tr1a.

Then, the second switching device Q2 is turned on again.

Of these operations, the full-wave rectifier
In the portion where the peak value of the voltage 13 is high, the on-period of the second switching device Q2 is relatively short, and in the portion where the peak value is low, the on-period of the second switching device Q2 is relatively long. The change in the ON period may be continuous or stepwise with respect to the peak value.

As described above, when the on-period of the second switching device Q2 is relatively lengthened in the portion where the peak value is low, the amplitude and the peak value of the resonance voltage are changed to the second switching device Q2.
This is larger than when the on-period of Q2 is relatively short. That is, in a portion where the peak value of the unsmoothed DC voltage is low, the voltage charged in the second capacitor C3 decreases according to the peak value, and the initial current flowing into the second capacitor C3 increases. Therefore, in the period where the peak value of the non-smoothed DC voltage is low, the voltage can be boosted more than in the portion where the peak value is high.

Also, during the period when the peak value is low, the current flowing through the first switching device Q1 is cut off at a relatively small stage, so that the initial resonance current value after the first switching device Q1 is turned off is reduced. Although the resonance voltage is increased due to the charging voltage of the second capacitor C3, the peak voltage of the non-smooth DC voltage is reduced without excessively increasing the voltage at the valleys, although the resonance voltage is increased. During the period,
The voltage can be boosted as desired, and the output voltage can be smoothed.

Further, since the current from the full-wave rectifier 13 flows over the entire period of the non-smoothed DC voltage, this current increases the input power factor and reduces the input current. The high frequency component of the input current is removed by the filter circuit 12.

In the current of the fluorescent lamp FL, low frequency ripple is reduced.

On the other hand, the discharge lamp lighting device 11 includes a fluorescent lamp FL.
In the preheating and starting states before the lights are turned on, if the oscillation frequencies of the first switching device Q1 and the second switching device Q2 are changed, the output voltage changes as shown in FIG. That is, as shown in FIG.
, FLb as the pseudo resistor Ra and the pseudo resistor Rb,
When the lamp voltage VL is measured, the input voltage is 10 V, the coupling constant of the insulating transformer Tr1 is k = 0.792, the primary winding Tr1a
Of 0.357 mH, the inductance of the secondary winding Tr1b is 2.052 mH, the resistance of each of the pseudo resistors Ra and Rb is 10Ω, and the capacitance of the capacitor C4 is 6
With 800 pF, the series resonance frequency f1 is 73 kHz.
z, the parallel resonance frequency f2 is 45 kHz, and the maximum point f3 is 2
Appears at 3 kHz. In a portion where the resonance frequency is equal to or higher than f2 and equal to or lower than the series resonance frequency f1, in a light load state in which the fluorescent lamp FL is not lit, the load becomes a capacitive load and the phase is advanced.
It is not preferable in the preheating and starting states before the FL is turned on.

Here, the cause of the appearance of the maximum point f3 will be described.

First, as shown in FIG. 5, a negative sinusoidal voltage is applied to the insulating transformer Tr1 when the second switching device Q2 is turned on.
When the switching device Q1 is turned on, a positive rectangular wave voltage is applied. When the second switching device Q2 is turned on, a resonance current flows between the pseudo resistors Ra, Rb and the capacitor C4 serving as loads and the second capacitor C3, and the second capacitor C3 and the first capacitor C3. When the sum of the voltages across C2 becomes equal to the input voltage, the full-wave rectifier 13
Current flows from the At this time, since a DC voltage is applied to the first capacitor C2, a difference between the input voltage and the DC voltage of the second capacitor C3 is applied to the insulating transformer Tr1. When the first switching device Q1 is turned on, the energy stored in the first capacitor C2 is transferred to the first capacitor C2, the primary winding Tr1a of the isolation transformer Tr1, and the first capacitor C2.
Is discharged through the path of the switching device Q1 and the first capacitor C2, a pulse-like voltage having a peak value equal to that of the first capacitor C2 is applied to the insulating transformer Tr1.
And it is induced in the secondary winding Tr1b of the isolation transformer Tr1,
Drives the pseudo resistors Ra and Rb of the load and resonates. Further, since the waveform shown in FIG. 5 includes a pulse-like voltage, a harmonic component with respect to the switching frequency is included. Since the harmonic component resonates, the maximum output at the maximum point f3 is obtained. It is thought to appear.

Therefore, if a portion of the inductive load which is higher than the maximum point f3 and lower than the parallel resonance frequency f2 is used, the fluorescent lamp FL can be used.
Prior to the lighting state, no fast-phase switching occurs.

Therefore, in the preheating or starting state before the fluorescent lamp FL is turned on, the pair of switching devices Q1 and Q2 are controlled in the frequency range from the maximum point f3 to the parallel resonance frequency f2.

Further, when the fluorescent lamp FL is not lit, the on-duty of the second switching device Q2 is reduced at a constant frequency in the frequency range from the maximum point f3 to the parallel resonance frequency f2 or less. The fluorescent lamp FL is preheated at a relatively low voltage.

When the preheating of the fluorescent lamp FL is completed,
The frequency is not changed, the on-duty of the second switching device Q2 is lengthened, the output is made slightly higher, and the fluorescent lamp FL is started.

Although the phase switching does not occur even at a frequency higher than the series resonance frequency f1, the frequency becomes extremely high because the fluorescent lamp FL is preheated more than necessary and the frequency becomes extremely high. And a frequency equal to or lower than the parallel resonance frequency f2 is preferable.

When changing the output voltage at the time of preheating and starting the fluorescent lamp FL, the same applies to the case where the on-duty is changed and the frequency is changed without changing the on-duty. The effect of can be obtained.

Further, when the fluorescent lamp FL is turned on, the fluorescent lamp FL is no longer lightly loaded, and the output voltage and characteristics with respect to frequency change, and the first switching device Q1 and the second switching device Q2 near the parallel resonance frequency f2. Even if the oscillation is controlled around the parallel resonance frequency f2, the phase switching does not occur.

Therefore, in any of the preheating, starting and lighting states, the first switching device Q1 and the second switching device Q2 do not perform the fast switching, and apply an appropriate voltage to the fluorescent lamp FL. Can be applied.

On the other hand, after the fluorescent lamp FL is turned on by, for example, an external signal, the output voltage can be changed by controlling the ON period of the second switching device Q2, and the fluorescent lamp FL can be dimmed and lit. . That is, when the ON period of the second switching device Q2 is relatively increased, the output voltage increases, and when the ON period is relatively reduced, the output voltage decreases.

When the power is turned on, the first capacitor
The inrush current to C2 is that the primary winding Tr1a of the isolation transformer Tr1 is connected in series to the first capacitor C2, and that the second switching device Q2 is turned on and off at a high frequency. Thus, it is reduced.

Further, an end-of-life detecting means for detecting the end of the life of the fluorescent lamp FL or an abnormality detecting means for detecting the detachment of the fluorescent lamp FL is provided to detect the end of the life of the fluorescent lamp FL or the detachment of the fluorescent lamp FL. Then, even if the fluorescent lamp FL is turned on, the fluorescent lamp FL
By controlling in a state before is turned on, it is possible to suppress the output voltage and to prevent the early phase switching. In this case, the oscillation frequency may be set to a value near or lower than the parallel resonance frequency f2.

In the above embodiment, the full-wave rectifier
Assuming that the state in which the forward current flows from 13 is the forward polarity of the current flowing in the first switching device Q1, the switching control unit 14 may control the first resonance device located on the side that charges the first capacitor C2, for example. The first switching device Q1 is turned on with the current flowing through the switching device Q1 having the opposite polarity, and turned off after the current has turned to the forward polarity, but is not limited to this.

Here, the first switching device Q1 includes:
As shown in FIG. 6, a gradually attenuating resonance current flows.

Then, for example, as shown in FIG.
The first switching device Q1 is turned on in a state where the current flowing through the first switching device Q1 for resonance, which is located on the side where the capacitor C2 is charged, has a reverse polarity. May be turned off, and then turned off after turning to forward polarity. In addition, the same effect can be obtained if the polarity is changed to the forward polarity at the end of FIG. 7 and before the polarity is further changed to the opposite polarity.

As shown in FIG. 8, for example, the first switching device Q1 on the side that charges the first capacitor C2
Is turned on in a state of reverse polarity, and when n is a natural number, the current may be turned off after the (n + 1) th, that is, after the second time, the current has turned to the forward polarity. When the current flowing through the switching device Q1 is turned on in a state of reverse polarity, and this reverse state is set as the first time and n is a natural number, this current turns to the first forward polarity and the second reverse polarity. The same effect can be obtained by turning off before turning to the second forward polarity, turning to the (n + 1) th forward polarity, and turning to the (n + 1) th reverse polarity.

That is, the resonance current flowing through the first switching device Q1 may be turned off in the forward polarity state after the second time, and if the first switching device Q1 is not turned off in the reverse polarity state, the phase advance may occur. Switching does not occur and a large stress is not applied to the first switching device Q1 and the like.

Further, the output voltage can be controlled depending on at which stage of the forward polarity of the resonance current the first switching device Q1 is turned off.

At which stage the first switching device Q1 is turned off, the number of forward-polarity currents flowing through the first switching device Q1 is counted and set at a predetermined number of stages. The time during which the first switching device Q1 is on may be measured, or the control may be performed by controlling both the on time and the off time of the first switching device Q1.

The same effect as in the above embodiment can be obtained even if the connection positions of the first switching device Q1 and the second switching device Q2 are reversed. In this case, the respective switching devices for controlling the ON period are also reversed.

In the above embodiment, a configuration using a field effect transistor has been described. However, a switching element having no parasitic diode, such as a bipolar transistor, can be similarly configured, and a bipolar transistor can be used. When used, a diode whose conduction direction is reversed may be connected between the collector and the emitter, or when a diode is connected between the emitter and the base, this diode may be used.

Further, the same effect can be obtained by using not only an insulating transformer but also an autotransformer or a coil.

[0063]

According to the first aspect of the present invention, before the discharge lamp is turned on, the switching control means controls the series resonance frequency of the output circuit and the load circuit connected to the output circuit. Since the pair of switching devices are controlled at a frequency lower than any of the parallel resonance frequencies, the load does not become capacitive and the phase switching is not performed, so that a large stress can be prevented from being applied to the pair of switching devices.

According to the discharge lamp lighting device of the second aspect,
In addition to the discharge lamp lighting device according to claim 1, the switching control means controls the on-duty by changing the on-duty at a constant frequency before the discharge lamp is turned on. The output can be controlled in each state before the discharge lamp is turned on at the time of starting or the like.

According to the discharge lamp lighting device of the third aspect,
In addition to the discharge lamp lighting device according to claim 1, the switching control means controls at a frequency near the parallel resonance frequency after the discharge lamp is turned on, so that the discharge lamp is turned on and the load changes. After that, control can be performed without leading to phase switching.

According to the discharge lamp lighting device of the fourth aspect,
The switching control means turns on the current flowing through one of the switching devices located on the side where the first capacitor is charged, in a state of reverse polarity, and this current turns to forward polarity, turns to reverse polarity again, turns to forward polarity. After that, the phase switching is not performed, so that it is possible to prevent a large stress from being applied to the pair of switching devices.

According to the discharge lamp lighting device of the fifth aspect,
The switching control means turns on the current flowing through one of the switching devices located on the side where the first capacitor is charged, in a state of reverse polarity, and when n is a natural number, this current becomes the (n + 1) th forward polarity. Since it turns off after turning,
Since the phase switching does not occur, it is possible to prevent a large stress from being applied to the pair of switching devices.

According to the discharge lamp lighting device of the sixth aspect,
The switching control means turns on the current flowing through one of the switching devices located on the side where the first capacitor is charged, in a state of reverse polarity, and when n is a natural number, this current becomes the (n + 1) th forward polarity. Since it turns off after turning,
Since the phase switching does not occur, it is possible to prevent a large stress from being applied to the pair of switching devices.

According to the discharge lamp lighting device of the seventh aspect,
In addition to the discharge lamp lighting device according to any one of claims 4 to 6, the operation of the switching control means is an operation before the discharge lamp is turned on, so that a light load state before the discharge lamp is turned on. However, since the phase switching does not occur, it is possible to prevent a large stress from being applied to the pair of switching devices.

According to the discharge lamp lighting device of the eighth aspect,
In addition to the discharge lamp lighting device according to any one of claims 4 to 7, the operation of the switching control means is an operation in at least one of a state at the end of the life of the discharge lamp and a state of removing the discharge lamp. Even at the end of lamp life and when the discharge lamp is removed, fast-phase switching does not occur, so that it is possible to prevent a large stress from being applied to a pair of switching devices.

According to the illuminating device of the ninth aspect, since the discharge lamp lighting device of any one of the first to eighth aspects is provided, each effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a discharge lamp lighting device of the present invention.

FIG. 2 is a perspective view showing an appearance of the lighting device.

FIG. 3 is a graph showing a relationship between an oscillation frequency and an output voltage.

FIG. 4 is a circuit diagram in which the relationship between the oscillation frequency and the output voltage is measured.

FIG. 5 is a waveform diagram of a driving voltage for driving the pair of switching devices.

FIG. 6 is a waveform chart showing a voltage generated in an insulating transformer by turning on and off a first switching device and a second switching device.

FIG. 7 is a waveform chart showing on / off control of a first switching device according to another embodiment of the present invention.

FIG. 8 is a waveform chart showing on / off control of a first switching device according to another embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Appliance main body 11 Discharge lamp lighting device 13 Full-wave rectifier 14 Switching control means C2 First capacitor C3 Second capacitor e Commercial AC power supply FL Fluorescent lamp as discharge lamp Q1, Q2 Switching device Tr1 Insulating transformer Tr1b as inductor Secondary winding as output circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiichi Shimizu 4-3-1 Higashi Shinagawa, Shinagawa-ku, Tokyo Toshiba Lighting & Technology Corporation

Claims (9)

[Claims] 1. A rectifier for rectifying an output voltage of an AC power supply and outputting a non-smooth DC voltage; provided in series between output terminals of the rectifier, alternately at a frequency higher than an output frequency of the rectifier. A pair of switching devices that are turned on and off; a series circuit of a first capacitor and an inductor that is provided between both terminals of one of the switching devices and that smoothes the output frequency of the rectifier; A second capacitor that resonates in cooperation with an inductor when turned off; an output circuit that lights a discharge lamp based on resonance of the inductor and the second capacitor; an output circuit before the discharge lamp is turned on And a pair of switching devices at a frequency lower than either the series resonance frequency or the parallel resonance frequency of the load circuit connected to the output circuit. Switching control means for controlling;
A discharge lamp lighting device comprising: 2. The discharge lamp lighting device according to claim 1, wherein the switching control means controls the on-duty by changing the on-duty at a constant frequency before the discharge lamp is turned on. 3. The lighting of the discharge lamp according to claim 1, wherein the switching control means controls the frequency by changing the frequency to a frequency near the parallel resonance frequency after the discharge lamp is turned on. apparatus. 4. A rectifier for rectifying an output voltage of an AC power supply to output a non-smoothed DC voltage; provided in series between output terminals of the rectifier, and turned on and off in a forward polarity from the rectifier. And a pair of switching devices that are turned on and off alternately at a frequency higher than the output frequency of the rectifier in the on state with the opposite polarity; provided between both terminals of one of the switching devices, with respect to the output frequency of the rectifier. A series circuit of a first capacitor and an inductor acting as a smoother;
A second capacitor that resonates in cooperation with the inductor in response to turning on and off of the pair of switching devices; an output circuit that turns on the discharge lamp based on resonance of the inductor and the second capacitor; Switching control means for turning on a current flowing through one of the switching devices located on the charging side in a state of reverse polarity, turning the current to a forward polarity, turning back to a reverse polarity, turning back to a forward polarity, and then turning off. Discharge lamp lighting device characterized by comprising: 5. A rectifier for rectifying an output voltage of an AC power supply to output a non-smoothed DC voltage; provided in series between output terminals of the rectifier, and turned on and off in a forward polarity from the rectifier. And a pair of switching devices that are turned on and off alternately at a frequency higher than the output frequency of the rectifier in the on state with the opposite polarity; provided between both terminals of one of the switching devices, with respect to the output frequency of the rectifier. A series circuit of a first capacitor and an inductor acting as a smoother;
A second capacitor that resonates in cooperation with the inductor in response to turning on and off of the pair of switching devices; an output circuit that turns on the discharge lamp based on resonance of the inductor and the second capacitor; Switching control means for turning on the current flowing through one of the switching devices located on the charging side in a state of reverse polarity and turning off after the current has turned to the (n + 1) th forward polarity when n is a natural number; A discharge lamp lighting device comprising: 6. A rectifier for rectifying an output voltage of an AC power supply and outputting a non-smooth DC voltage; provided in series between output terminals of the rectifier, alternately at a frequency higher than an output frequency of the rectifier. A pair of switching devices that are turned on and off; a relatively large-capacity first capacitor provided in parallel with one of the switching devices; and a first capacitor interposed between the pair of switching devices and between the first capacitors. An inductor; a second capacitor having a capacitance smaller than a first capacitor forming a resonance circuit with the other switching device and the inductor during an ON period of the other switching device; and a discharge lamp based on resonance of the inductor and the second capacitor. And an output circuit for lighting the first capacitor; the current flowing through one of the switching devices located on the side for charging the first capacitor has a reverse polarity. A switching control means for turning on in a state, and when n is a natural number, turning off after this current has turned to the (n + 1) th forward polarity. 7. The discharge lamp lighting device according to claim 4, wherein the operation of the switching control means is an operation before the discharge lamp is turned on. 8. The discharge control according to claim 4, wherein the operation of the switching control means is an operation in at least one of the state at the end of the life of the discharge lamp and the time of removal of the discharge lamp. Lighting device. 9. An illuminating device comprising: the discharge lamp lighting device according to claim 1; and a fixture main body provided with the discharge lamp lighting device and mounted with a discharge lamp.