JPH11102796A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device, in which a pressure rise of a DC voltage obtained by rectifying and smoothing an AC power supply is reduced. SOLUTION: A power conversion circuit 10 converts a DC voltage of a smoothing capacitor C1 obtained by rectifying and smoothing an AC power supply Vs to a high-frequency voltage, supplies it to load circuits 11 and 12 , and lights discharge lamps La1 and La2 at a high frequency. The power conversion circuit 10 preheats one discharge lamp La1 in advance by a given time, charge operating frequency, and starts up the discharge lamp La1 . Thereafter, the power conversion circuit 10 makes the operating frequency changed, preheats the remaining discharge lamp La2 in advance by a given time, and further, has the operating frequency changed to start the discharge lamp La2 . Here, at the time of discharge lamp startup, an input current corresponding to one resonant current flowing portion to a load by one lamp is led in, thus enabling reduction of pressure rise of the DC voltage, as compared with a case of simultaneous two-lamp start up.

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 which converts a DC voltage obtained by rectifying and smoothing an AC power supply into a high-frequency voltage and supplies it to a discharge lamp.

[0002]

2. Description of the Related Art FIG.
2. There was one having the circuit configuration shown in FIG. This discharge lamp point
In the lighting device, the transformer T_Two, Capacitor C_Two, C_ThreeThan
Filter circuit LPF and the filter circuit LPF
Rectifier D for full-wave rectification of AC power supply Vs input through
B and a diode D between the DC output terminals of the full-wave rectifier DB.
₁Capacitor C connected through₁And Daioh
Do D₁Capacitor C connected in parallel with_FourAnd the smoothing con
Densa C₁Turns on alternately at high frequency connected between both ends of
MOS field-effect transistor (hereinafter referred to as MOS)
FET)₁, Q_TwoAnd a primary winding n₁
Is connected to a full-wave rectifier DB and a diode D₁At the connection point
Connected transformer T₁And one end is a transformer T₁Primary
Winding n₁And the other end is connected to the MOSF
ETQ₁, Q_TwoC connected to the connection point of
_FiveAnd the transformer T₁Secondary winding n_TwoTwo sets connected to
Load circuit 1 ₁, 1_TwoTo form the power conversion circuit 10.
You.

Here, the load circuit 1₁Is the transformer T₁of
Secondary winding n_TwoInductor L₁Through both filaments
Discharge lamp consisting of, for example, a fluorescent lamp to which the power supply side terminal of
La ₁And the discharge lamp La₁Non-power end of both filaments
Capacitor C connected between children₆And the load
Circuit 1_TwoIs the transformer T₁Secondary winding n_TwoInductor
L_TwoThe power supply terminals of both filaments are connected via
For example, a discharge lamp La composed of a fluorescent lamp_TwoAnd the discharge lamp La_Twoof
The capacitor connected between the non-power supply terminals of both filaments
Sa C₇It is composed of

[0004] The operation of this circuit will be briefly described below. In this circuit, a half-bridge inverter circuit is composed of MOSFETs Q ₁ and Q ₂ , inductors L ₁ and L ₂ , capacitors C ₅ , C ₆ and C ₇ and discharge lamps La ₁ and La ₂ , and the MOSFETs Q ₁ and Q ₂ are illustrated. is turned on and off alternately at a high frequency by a control circuit not, converts the DC voltage smoothed by the smoothing capacitor C ₁ to the high-frequency AC voltage, the discharge lamp La _1, La ₂ is made to high frequency lighting. Here, in the load circuit 1 ₁ is configured the resonance circuit 2 ₁ from the capacitor C ₆ and an inductor L _1, the load circuit 1 _2, the resonance circuit 2 ₂ and a capacitor C ₇ and the inductor L _2. Further, the capacitors C ₆ and C ₇ constitute preheating current supply paths for the discharge lamps La ₁ and La ₂ , respectively. The capacitor C ₅ is a coupling capacitor for DC component cut.

In this circuit, the MOSFET Q_TwoIs on
(MOSFET Q₁Turns off), the capacitor C₁Or
Capacitor C_Four→ Transformer T₁Primary winding n₁→ Con
Densa C_Five→ MOSFET Q_Two→ Capacitor C₁Path
Current flows through the capacitor C_FourIs charged. here,
The output voltage of the full-wave rectifier DB is | V_in｜, smoothing capacitor
C₁V across_C1, Capacitor C_FourV across
_C4And | V_in|> V_C1-V_C4When the relationship is established,
Wave rectifier DB to transformer T₁Primary winding n₁→ Conde
Sensor C_Five→ MOSFET Q_Two→ On the route of the full-wave rectifier DB
Input current I_INFlows. Next, MOSFETQ₁Is on
(MOSFET Q_TwoTurns off), the capacitor C_FourBut
Discharge, capacitor C_FourFrom MOSFETQ₁→ Con
Densa C_Five→ Transformer T₁Primary winding n₁→ Capacitor
C_FourA current flows in the reverse direction in the path. That is, full wave
DC output terminal of current transformer DB and capacitor C₁Inserted between
Capacitor C_FourIs a vibration element due to inverter resonance
And the capacitor C _FourIs the output of the full-wave rectifier DB
Voltage | V_in| And capacitor C₁Voltage V_C1The difference between
Since the voltage is shared, the output voltage of the full-wave rectifier DB |
V_in| Is the capacitor C ₁Voltage V_C1In the lower case
Also the input current I_INFlows at high frequency, improves input distortion,
The power factor of the power is improved.
). In addition, high frequency components are generated by the filter circuit LPF.
The input current waveform with the components removed is a sine
It can be a wave waveform.

[0006]

DISCLOSURE OF THE INVENTION Discharge lamp lighting of the above configuration
In the device, the input power drawn by the input distortion improvement operation
Style I_INOf the transformer T₁Primary
Winding n₁Current I flowing through_n1Is approximately one third. Ma
The transformer T₁Primary winding n₁Current I flowing through _n1Is
Transformer T₁Secondary winding n_TwoThe boost ratio to the current flowing through
It is almost equal to the digit value.

At this time, the transformer T₁Has a small boost ratio,
Transformer T₁Primary winding n₁Current I flowing through_n1Less
The input current I drawn_INRun out of
The smoothing capacitor C₁Voltage V_C1Decreases and smoothes
Capacitor C₁Voltage V _C1Is the output of the full-wave rectifier DB
Voltage | V_inWhen the peak value of |
Input current distortion due to the flow of a pulse current like the put type
Worsens. On the other hand, transformer T₁Large boost ratio,
Lance T₁Primary winding n₁Current I flowing through_n1Is bigger
The current I_n1MOSF included in the path through which
ETQ₁, Q_TwoSwitching loss increases.
Road efficiency will be reduced.

Also, since the input current I _IN flows equivalently through the discharge lamp, a current dependent on the discharge lamp flows. However, in practice, the input distortion improvement operation described above causes the resonance of the half-bridge inverter to be reduced. The input current I _IN flows in high frequency as a part of the resonance current in a time division manner with respect to the current. Thus, when designing a transformer T ₁ in the circuit as the input current I _IN in accordance with the resonance current flowing to the discharge lamp is drawn, the discharge lamp La _1, transformer T ₁ according to the load current flowing through the La ₂ It is necessary to adjust the step-up ratio so that a pulse current like the capacitor input type does not flow in the input current I _IN . Here, assuming that the current flowing through the inductor L ₁ is I _L1 , the current flowing through the inductor L ₂ is I _L2 , and the step-up ratio of the transformer T ₁ is 1: n, the input current I _IN is expressed by the following equation.

I _IN ≒ I _n1 / 3 ≒ n × (I _L1 + I _L2 ) / 3 In such a circuit, when two different discharge lamps are lit in parallel, usually, the start of the discharge lamp is considered. FIG.
A resonance curve as shown in Fig. 7 is designed. G in FIG.
The resonance curve of the resonant circuit 2 _1, H in FIG. 13 is a resonance curve of the resonant circuit 2 _2, resonance curves G, H of the resonant circuit 2 _1, 2 ₂ are substantially equal.

When lighting the discharge lamps La ₁ and La ₂ , first, pre-heating is performed for a predetermined time at the operating frequency f ₁ , and a predetermined pre-heating current is supplied to the filaments of the discharge lamps La ₁ and La ₂ . At this time, the discharge lamps La ₁ , La ₂
Of the discharge lamps La ₁ , La ₂
So it does not light, and designing a resonant circuit 2 _1, 2 _2.

Next, the direction in which the resonance becomes stronger (the operating frequency f
Changing the operating frequency f in the direction) of lowering the frequency f ₂
At (<f ₁ ), the discharge lamps La ₁ and La ₂ are started. In practice, the voltage at which discharge starts differs depending on the ambient temperature and the like. Therefore, the discharge lamps La ₁ and La ₂ start discharging before the operating frequency f changes from f ₁ to f ₂ . At this time, predetermined starting voltage applied to both ends of the discharge lamp La _1, La ₂ is generated by the no-load resonance, the discharge lamp La _1, La ₂
Is turned on, but a much larger current flows through the inductors L ₁ and L ₂ until the discharge lamps La ₁ and La ₂ are turned on as compared to when the discharge lamps are turned on. Therefore, at the time of starting, despite the fact that there is no power consumption in the discharge lamp, a very large input current I _IN is drawn in by the input distortion improvement operation, so that the voltage V _C1 across the smoothing capacitor C ₁ greatly increases. Therefore, there is a problem that stress applied to elements constituting a circuit increases, a breakdown voltage of the elements increases, and a cost increases due to the use of an element having a high breakdown voltage. In addition, when the withstand voltage of the switching element is increased, the on-resistance of the switching element is increased, which causes a problem that a switching loss increases and a temperature of the switching element increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a discharge lamp lighting device in which the voltage across a smoothing capacitor is reduced when the discharge lamp is started. .

[0013]

In order to achieve the above object, according to the first aspect of the present invention, a DC voltage obtained by rectifying and smoothing an AC power supply is converted into a high frequency, and a plurality of DC voltages are converted via a transformer or an inductor. A power conversion circuit that supplies high-frequency power to a load circuit including the discharge lamp and draws an input current corresponding to a resonance current flowing through the discharge lamp, the power conversion circuit first starts at least one discharge lamp, Since the remaining discharge lamps are started by varying the operating frequency, an input current corresponding to the resonance current flowing through one discharge lamp is drawn at the time of starting, so that the input current is reduced and rectification is performed. The boosting of the DC voltage obtained by smoothing can be reduced. In addition, since there is a discharge lamp that has already been started at the time of starting the second and subsequent lamps, power is consumed by the discharge lamp, so that the DC voltage boost obtained by rectifying and smoothing can be further reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, the power conversion circuit first starts the discharge lamp having a small resonance current flowing through the load circuit, and then changes the operating frequency to change the remaining discharge lamps. Has been started. Here, since the input current according to the resonance current flowing through the discharge lamp is drawn in, the discharge current having a small resonance current is first started, so that the input current at the time of starting is reduced, and the rectified and smoothed DC voltage is obtained. Boosting can be further reduced.

According to a third aspect of the present invention, in the first aspect of the invention, the power conversion circuit first starts the discharge lamp having a large rated power, and then starts the remaining discharge lamps by changing the operating frequency. Since the no-load resonance frequency of a discharge lamp with a large rated power is higher than that of other discharge lamps,
Since it is close to the resonance point at the time of rated lighting, the output power can be increased.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the power conversion circuit first starts the discharge lamp having a high applied start voltage, and then changes the operating frequency to start the remaining discharge lamps. ing. Here, when starting the second and subsequent discharge lamps, since the first discharge lamp has already been started, it is possible to reduce the step-up of the DC voltage obtained by rectification and smoothing. Since it becomes difficult to secure the applied start voltage of the second and subsequent discharge lamps, it is possible to start the discharge lamp more reliably by starting the discharge lamp having the higher applied start voltage first.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the power conversion circuit first starts the discharge lamp having a large preheating current, and then starts the remaining discharge lamps by changing the operating frequency. ing. Here, if the starting applied voltage is set to a certain voltage or less, the higher the operating frequency, the higher the preheating current, so starting the discharge lamp with the higher preheating current first sufficiently reduces the preheating current. Can be secured.

According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the power conversion circuit is connected via a diode between a full-wave rectifier for full-wave rectification of the AC power supply and a DC output terminal of the full-wave rectifier. A first capacitor for smoothing, a second capacitor connected in parallel with the diode,
First and second switching elements connected between both ends of the first and second capacitors, and first and second switching elements connected in anti-parallel with the first and second switching elements, respectively.
And a series circuit comprising a primary winding of a transformer and a third capacitor connected between a connection point of a DC output terminal and a diode of the full-wave rectifier and a connection point of the first and second switching elements. And a load circuit including a plurality of discharge lamps connected to the secondary winding of the transformer. In the invention according to claim 7, the power conversion circuit includes a full-wave rectifier that performs full-wave rectification on the AC power supply. A smoothing first capacitor having one end connected to the low potential side of the DC output terminal of the full-wave rectifier; and first and second alternately turned on / off connected between both ends of the first capacitor. A series circuit of switching elements, first and second rectifying elements connected in anti-parallel with the first and second switching elements, respectively, and a fourth capacitor connected between the DC output terminals of the full-wave rectifier; DC output terminal of full-wave rectifier A transformer having a primary winding connected between a potential side and a connection point between the first and second switching elements, and a load circuit including a plurality of discharge lamps connected to a secondary winding of the transformer. According to the present invention, the power conversion circuit comprises a first capacitor for smoothing, and first and second switching elements connected between both ends of the first capacitor and turned on and off alternately. And the first and second
First and second rectifying elements connected in anti-parallel to the switching elements of the first and second types, third and fourth rectifying elements connected between both ends of the first capacitor, and one end of the primary winding of the first and second rectifying elements. A transformer connected to a connection point of the second switching element and having the other end of the primary winding connected to a connection point of the third and fourth rectification elements via an AC power supply; and a secondary winding of the transformer. And a load circuit including a plurality of discharge lamps connected between both ends of
At the time of starting, an input current corresponding to a resonance current flowing through one discharge lamp is drawn, so that the input current can be reduced and the DC voltage boost obtained by rectifying and smoothing can be reduced. In addition, since there is a discharge lamp that has already been started at the time of starting the second and subsequent lamps, power is consumed by the discharge lamp, so that the DC voltage boost obtained by rectifying and smoothing can be further reduced.

According to a ninth aspect of the present invention, in the sixth to eighth aspects of the present invention, the load circuit comprises at least a resonance inductor, a fifth resonance capacitor, and a discharge lamp. In the invention of claim 9, the discharge lamp comprises a fluorescent lamp, a fifth capacitor is connected between the non-power supply side terminals of the filaments at both ends of the fluorescent lamp, and the power supply side of one of the filaments of the fluorescent lamp. One end of the inductor is connected to the terminal, and the secondary winding of the transformer is connected between the power supply side terminal of the other filament of the fluorescent lamp and the other end of the inductor. The boosting of the DC voltage can be reduced, and the fluorescent lamp can be reliably turned on.

[0020]

Embodiments of the present invention will be described with reference to the drawings.
I will explain. (Embodiment 1) A circuit diagram of a discharge lamp lighting device of the present embodiment is shown.
As shown in FIG. In this discharge lamp lighting device, the transformer T_Two,
Capacitor C_Two, C_ThreeA filter circuit LPF comprising:
AC power supply Vs input through filter circuit LPF
Full-wave rectifier DB for full-wave rectification and DC of full-wave rectifier DB
Diode D between output terminals₁The first connected via
Smoothing capacitor C as a capacitor₁And the diode D ₁
A capacitor C as a second capacitor connected in parallel with
_FourAnd the smoothing capacitor C₁High frequency connected between both ends of
1st and 2nd switching elements which are turned on and off alternately by
Simple MOSFET Q₁, Q_TwoSeries circuit and primary winding
n₁Is connected to a full-wave rectifier DB and a diode D₁Connection
Transformer T connected to a point₁And one end is a transformer T₁of
Primary winding n₁And the other end is connected to MO
SFETQ₁, Q_TwoThe third condenser connected to the connection point of
Capacitor C_FiveAnd the transformer T₁Secondary winding n
_TwoSets of load circuits 1 connected to₁, 1_TwoPower change from
The conversion circuit 10 is configured. In addition, MOSFETQ₁, Q_Two
1st and 2nd alignment by the parasitic diode (not shown)
A flow element is configured.

Here, the load circuit 1₁Is the transformer T₁of
Secondary winding n_TwoInductor L₁Through both filaments
Discharge lamp consisting of, for example, a fluorescent lamp to which the power supply side terminal of
La ₁And the discharge lamp La₁Non-power end of both filaments
A capacitor C as a fifth capacitor connected between the terminals₆
And a load circuit 1_TwoIs the transformer T₁Secondary
Winding n_TwoInductor L_TwoThrough both filaments
Discharge lamp La composed of, for example, a fluorescent lamp to which the source side terminal is connected
_TwoAnd the discharge lamp La_TwoBetween the non-power supply terminals of both filaments
C, the fifth capacitor connected to₇And
And two discharge lamps La₁, La_TwoIn parallel
It is configured to light up. Where inductor L₁Passing
And capacitor C₆From resonance circuit 2₁Is configured and
Kuta L_TwoAnd capacitor C₇From resonance circuit 2_TwoIs composed
It is. Resonant circuit 2₁, 2_TwoFig. 2 shows the resonance curve of
As shown in FIG. 2, A is
Resonant circuit 2₁B in FIG. 2 indicates a resonance curve.
Road 2_TwoIt is a resonance curve of FIG. The horizontal axis in FIG.
The wave number f, and the vertical axis is the inductor L₁, L_TwoEach flow
Current I_L1, I_L2It is.

In a conventional discharge lamp lighting device, two discharge lamps are used.
La₁, La_TwoWhile preheating and starting at the same time
In the present invention, one of the two lamps is first preheated and started.
After turning on the lights, the remaining one light is preheated and started.
You. Hereinafter, the operation of this discharge lamp lighting device will be briefly described.
You. First, the operating frequency f₁In the resonance circuit 2₁Ahead
Row preheating current I₁₁To discharge one of the discharge lamps La₁At a given time
Preheat for a while. At this time, the resonance circuit 2_TwoThe current flowing through
Since it is very small compared to the preheating current, the discharge lamp La_Two
Does not lead to preheating. Thereafter, the power conversion circuit 10 operates.
Frequency f₁To f_TwoTo (f₁> F _Two),resonance
Circuit 2₁The resonance current of I₁₁To I₁₂To increase the discharge lamp
La₁To start. Operating frequency f₁To f_TwoUntil
While lowering, resonance circuit 2₁Becomes stronger, and the resonance current becomes
As it increases, the input current I_INIncreased, smoothing con
Densa C₁Voltage V_C1Is boosted. At this time,
Road 2_TwoIs weak, and the resonance circuit 2_TwoHas small resonance current
Therefore, the input current I_INIs the resonance circuit 2₁Large to the resonance current of
Depends.

In a conventional circuit, as shown in FIG.
Sea resonance circuit 2₁, 2_TwoThe resonance curves G and H of
Design and operating frequency f_TwoThe two discharge lamps La₁,
La _TwoAt the same time, and the operating frequency f_Twosmell
And inductor L₁, L_TwoCurrent I flowing through each₁₂, I_{twenty two}of
Sum (I₁₂+ I_{twenty two}) Dependent input current I_INIs retracted
Therefore, the smoothing capacitor C₁Voltage V_C1Is very large
It will be good. On the other hand, in the present invention, the resonance circuit 2₁Resonance of
Current (ie, discharge lamp La₁Resonance current for one lamp)
The corresponding input current is drawn. That is, the operation
Wave number f_TwoIn the inductor L₁, L_TwoElectricity flowing to each
Style I₁₂, I₂₀Sum (I₁₂+ I₂₀) Dependent input current I
_INIs drawn. At this time, the inductor L_TwoElectricity flowing through
Style I₂₀Is the current I in the case of the conventional circuit._{twenty two}Small enough for
Input current I_INBecomes smaller and the smoothing capacitor C
₁Voltage V_C1Can be reduced. In addition, the discharge lamp L
a ₁Power is consumed by lighting of the discharge lamp La.₁
And the smoothing capacitor C₁Voltage V_C1Is low
Down. Note that the discharge lamp La is actually₁Is the operating frequency f _Twoso
It does not always light, and the operating frequency f₁From
f_TwoStarting at a relatively low starting voltage until it drops to
However, in this circuit, the discharge lamp La₁For outgassing
Therefore, the discharge lamp La₁Is the operating frequency f_TwoAlso lit
It is assumed that it will not.

Next, the power conversion circuit 10 further reduces the operating frequency f from f ₂ to f ₃ , performs pre-heating of the discharge lamp La _{2 at} the operating frequency f ₃ for a predetermined time, and changes the operating frequency f from f ₃ to f _{3. The} discharge lamp La ₂ is started by lowering it to ₄ .
As in the case of the discharge lamp La _1, f the operating frequency f from f ₃
In the course of lowering the ₄ intensifies the resonance of the resonant circuit 2 _2, with an increase of the resonant current, the input current I _IN drawn increases. When this has the other discharge lamp La ₁ is already lit, as the operating frequency f is lowered, an increasing resonance of the resonance circuit 2 _1, because the power consumption of the discharge lamp La ₁ is increased, the discharge lamp La ₂ At the time of start-up, the boosting of the voltage V _C1 across the smoothing capacitor C ₁ can be reduced.

In the circuit of the present embodiment, the discharge lamp having the smaller resonance current at the time of starting the discharge lamp may be preheated and started first. Shows the resonance circuit 2 _1, 2 ₂ of the resonance curve A in this case, the B in FIG. here,
Resonance current I ₁₂ of the resonance circuit 2 ₁ during the discharge lamp start-up,
And smaller than the resonance current I ₂₂ of the resonant circuit _{2 2 (I 12 <I 22} ). The resonance circuit 2 _1, 2 ₂ of the resonance curve A shown by a solid line in FIG. 3, B is preheated discharge lamp La ₁ resonance current is small at the time of the discharge lamp start earlier, a design in the case of starting, resonant circuit 2 ₁ indicated by a broken line in FIG. 3, 2 ₂ of the resonance curve a ', B' may preheat the discharge lamp La ₂ resonance current is large at the time of the discharge lamp start earlier, is the design of the case of starting.

Preheating and starting the discharge lamp with a small resonance current first
(Resonance curves A and B), the operating frequency f_TwoSmell
Resonant circuit 2₁, 2_TwoResonance current I₁₂, I₂₀Sum (I₁₂
+ I ₂₀) According to the input current I_INFlows. On the other hand,
When preheating and starting a discharge lamp with a large current
A ', B'), operating frequency f_TwoResonant circuit in
2 ₁, 2_TwoResonance current I_Ten, I_{twenty two}Sum (I_Ten+ I_{twenty two})
Input current I_INFlows. Resonant current I_Ten, I₂₀Is
Swing circuit 2₁, 2_TwoIs weak and the difference between them is small,
Resonant current I₁₂, I_{twenty two}The sum of the resonance currents (I
₁₂+ I₂₀), (I_Ten+ I_{twenty two}) Is determined, and (I)₁₂+
I₂₀) <(I_Ten+ I_{twenty two}). That is, discharge lamp starting
Preheat and start the discharge lamp with a small resonance current
Input current I_INIs small
And smoothing capacitor C₁Voltage V_C1Is further reduced
You.

In the circuit of the present embodiment, the discharge lamp having a high rated output may be preheated and started first, and then the discharge lamp having a low rated output may be preheated and started. In the circuit shown in FIG. 1, for example a round tube fluorescent lamp of the discharge lamp La ₁ Output power 32W (model number FCL32), the discharge lamp La round tube fluorescent lamp ₂ a rated output 40W (model number FCL4
0), the resonant circuit 2 ₁ 4, 2 ₂ of the resonance curve C, and design D. Here, no-load resonance frequency f ₀₁ of the resonance circuit 2 ₁ is smaller with respect to the no-load resonance frequency f ₀₂ of the resonance circuit 2 _2, release the no-load resonance frequency designed resonance curve C, and D ing. In FIG. 4, the horizontal axis represents the operating frequency f, and the vertical axis represents the inductors L ₁ and L ₁ .
_The currents I _L1 , I _L2 flowing through _{2 and} the load outputs P ₁ , P ₂ of the discharge lamps La ₁ , La ₂ are taken. Here, E and F in FIG. 4 indicate the load outputs P ₁ and P ₂ of the discharge lamps La ₁ and La ₂ , respectively.

First, at the operating frequency f ₁ , after the discharge lamp La ₂ having a large rated output is preheated for a predetermined time, the power conversion circuit 10 lowers the operating frequency f from f ₁ to f ₂ ,
To start the discharge lamp La _2. When the discharge lamp La ₂ is turned, the resonance circuit 2 ₂ from no-load resonance, change in the resonant circuit including a resistance component after the lighting of the discharge lamp La _2. Next, the power conversion circuit 10 lowers the operating frequency f from f ₂ to f _3, pre-heats the discharge lamp La ₁ for a predetermined time, and further lowers the operating frequency f from f ₃ to f ₄ to change the discharge lamp La ₁ To start. When the discharge lamp La ₁ is lit, the resonance circuit 2 ₁ from no-load resonance, change in the resonant circuit including a resistance component after the lighting of the discharge lamp La _1.

Thereafter, the power conversion circuit 10 operates at the operating frequency f
To f_FourTo f_FiveDown to discharge lamp La₁, La_TwoSet
Turn on the case. At this time, the resonance circuit 2_TwoNo-load resonance frequency
Number f ₀₂Is the resonance circuit 2₁No-load resonance frequency f₀₁than
It is designed to be high, so operation at rated lighting
Frequency f_FiveThen, discharge lamp La₁Lighting components after lighting
Resonance circuit 2₁Compared to the discharge lamp La_TwoLighting after lighting
Circuit 2 containing components _TwoIs closer to the resonance point,
Output is easy to obtain.

As described above, it is better to first preheat and start the discharge lamp having the higher rated output, that is, to change the no-load resonance frequency of the discharge lamp having the higher rated output to the no-load resonance frequency of the discharge lamp having the lower rated output. In contrast, a larger design can reduce the voltage rise of the voltage V _C1 across the smoothing capacitor C ₁ at the time of starting, and can easily design a resonance circuit that can obtain a predetermined rated output of each discharge lamp at the rated lighting. I can do it.

Also, in the circuit of the present embodiment, the starting mark
Preheat and start the discharge lamp with high applied voltage first
Is also good. In the present embodiment, the second discharge lamp La_TwoStart
At the time of the first discharge lamp La₁Is already lit
Therefore, the already lit discharge lamp La₁Consumes power
Therefore, when starting two lamps at the same time as in the conventional circuit,
In comparison, the smoothing capacitor C₁Voltage V_C1Low boost
Is reduced. Therefore, the second discharge lamp La_TwoStart
In order to obtain a high starting applied voltage, the second resonance circuit
2_TwoStarting at a higher operating frequency
You. However, considering variations in parts, etc.,
Light up the second light because the margin of road design becomes small
Discharge lamp La _TwoStart applied voltage of the first lamp
Light La₁It is desirable that the applied voltage be lower than the starting applied voltage of
It is better to turn on the discharge lamp with the higher dynamic applied voltage first.
If the starting applied voltage is large, the no-load resonance frequency of the discharge lamp
It is better to design a higher
Sa C₁Voltage V_C1And the second light
The discharge lamp can be easily started.

Further, in the circuit of the present embodiment, when two different discharge lamps are turned on, the discharge lamp having a large preheating current may be preheated and started first.
When securing the preheating current of the discharge lamp La _1, La ₂ by the capacitor C _6, C _7, usually a capacitor C _6, C ₇
When the capacitance of the capacitors C ₆ and C ₇ is increased, it is difficult to secure a starting applied voltage at the time of starting the discharge lamp. _The capacitances of C ₆ and C ₇ are values satisfying both. Here, assuming that the operating frequency is f, the capacitance of the capacitor is C, and the starting applied voltage applied to the discharge lamp is V _La , the preheating current _If of the discharge lamp is expressed by equation (1).

I _f = 2πf · C · V _La (1) Here, from the equation (1), if the condition that the starting applied voltage V _La is set to be equal to or lower than a predetermined voltage value at which the discharge lamp is not turned on is determined,
Performing the pre-heating in the region where the operating frequency f is high can increase the pre-heating current even if the applied starting voltage is small. For example, a 32 W rated round tube fluorescent lamp (model number FCL
Requires a relatively large pre-heating current as in 32),
In addition, for a discharge lamp that is lit with a relatively low applied start voltage, if the preheating and starting are performed first, the operating frequency is increased, and a sufficient preheating current can be secured. It is desirable that the discharge lamp having a large preheating current be preheated and started first.

By the way, in the circuit of FIG.
Densa C₆, C₇Discharge lamp La ₁, La_TwoPreheating
But relatively high pre-heating current and relatively high
If a high starting applied voltage is required, the capacitor C₆, C
₇In the preheating by the capacitor C₆, C₇Resonance times including
Road design can be difficult. Therefore, as shown in FIG.
And load circuit 2₁And the transformer T₁Secondary winding n_TwoBoth
Inductor L connected between terminals₁And capacitor C₆of
Series circuit and capacitor C₆Is both filaments f₁, F
_TwoLamp La connected between the power supply side terminals of₁Composed of
And load circuit 2_TwoAnd the transformer T₁Secondary winding n_TwoBoth
Inductor L connected between terminals_TwoAnd capacitor C₇of
Series circuit and capacitor C₇Is both filaments f_Three, F
_FourLamp La connected between the power supply side terminals of_TwoComposed of
I do. And the transformer T₁Primary winding n₁And conden
Sa C_FiveBetween the transformer T_ThreePrimary winding n_ThreeInsert
Discharge lamp La₁One of the filaments f₁Power supply terminal
Capacitor C₈And transformer T_ThreeSecondary winding n_FourThrough
Connected to the non-power side terminal and the other filament
Tof_TwoTransformer T_ThreeSecondary winding n_Fiveas well as
Capacitor C₉To the non-power-supply side terminal. As well
And the discharge lamp La_TwoOne of the filaments f_ThreePower supply end of
The capacitor C_TenAnd transformer T_ThreeSecondary winding n₆To
Connected to the non-power supply side terminal via
Ment f_FourTransformer T_ThreeSecondary winding n₇
And capacitor C₁₁To the non-power side terminal via
Lance T_FiveSecondary winding n_Four~ N₇Depending on the current flowing through
And the discharge lamp La₁, La_TwoEven if you preheat
good.

Here, in the circuit shown in FIG.
Between the _first primary winding n ₁ and the capacitor C _5, but are connected to the primary winding n ₃ of the transformer T _3, as shown in FIG. 6, the transformer to the connection point of the diodes D ₁ and MOSFET Q ₁ Attach one end of the primary winding n ₃ of the T _3, the primary winding n
₃ the other end connected to one end of the capacitor C _16, and connect the other end of the capacitor C ₁₆ to the connection point of the primary winding n ₁ and the capacitor C ₅ of the transformer T _1, may constitute the preheating circuit .
It goes without saying that a preheating method other than the preheating methods shown in FIGS. 5 and 6 may be used.

Further, as shown in FIG. 7, the load circuit ₁ 1 of n sets in parallel with the secondary winding n ₂ of the transformer T _1, 1 ₂ ... 1 _n
May be connected, and the discharge lamps La _{1 to} L ₁ may be connected according to the load characteristics.
First preheating at least one light of the a _n, by starting, a smoothing capacitor C ₁ at the time of the discharge lamp start
Of the voltage V _C1 can be reduced. The resonance current, rated output, starting the applied voltage, depending on the load characteristics, such as preheating current may be sequentially lighting the discharge lamp La ₁ ~La _n of n lamp, a discharge lamp having lamp above After the lighting, the remaining discharge lamps may be sequentially turned on, or one discharge lamp may be turned on first, and then the remaining discharge lamps may be turned on at the same time.

(Embodiment 2) FIG. 8 is a circuit diagram of a discharge lamp lighting device according to this embodiment. Since the basic circuit configuration is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted. In the present embodiment, the voltage V _C1 across the smoothing capacitor C ₁ in the circuit of FIG.
, A control means 4 for generating a control signal in accordance with a detection signal of the voltage detection means 3, and a driving means 5 for driving MOSFETs Q ₁ and Q ₂ in accordance with a control signal of the control means 4. For example, when the first discharge lamp does not light, the voltage V _C1 across the capacitor C ₁ is provided.
Is prevented from being boosted to a design value or more and the element is destroyed.

As shown in FIG. 2, the control means 4 first operates
Working frequency f₁In the first discharge lamp La₁The predetermined time
Pre-heating and operating frequency f to f₁To f_TwoChange to
Discharge lamp La₁To start. Here, the predetermined starting voltage is
Despite being applied, the discharge lamp La₁Lights up
If not, the control means 4 further sets the operating frequency f to f_TwoFrom
f_ThreeTo change the capacitor C₁Voltage V_C1But
The voltage is further boosted, and the withstand voltage of the element may eventually be exceeded.
There is. Therefore, in the present embodiment, the voltage detecting means 3
Capacitor C₁Voltage V_C1Is a preset voltage value
When the control means 4 detects that the voltage exceeds
Generates a control signal to stop oscillation in response to a detection signal
Then, the driving means 5 outputs the MO signal based on the control signal of the control means 4.
SFETQ ₁, Q_TwoStop oscillation. in this way,
Due to some abnormality, the smoothing capacitor C₁Voltage across
V_C1Rises abnormally, the voltage detecting means 3 detects the voltage V
_C1Control means 4 detects an abnormal boost of
Q₁, Q_TwoOutputs control signal to stop switching
Therefore, destruction of the element can be prevented.

(Embodiment 3) FIG. 9 is a circuit diagram of a discharge lamp lighting device according to this embodiment. The operation of the power conversion circuit 10 at the time of starting the discharge lamp is the same as in the first embodiment, and a description thereof will be omitted. In this circuit, a full-wave rectifier DB for full-wave rectifying an AC power supply Vs input through a filter circuit LPF, and a smoothing capacitor C ₁ connected via a diode D ₁ between the DC output terminals of the full-wave rectifier DB. And a capacitor C ₁₂ connected between the DC output terminals of the full-wave rectifier DB.
And a series circuit of MOSFETs Q ₁ and Q ₂ alternately turned on and off at a high frequency connected between both ends of the smoothing capacitor C ₁ , and one end of a primary winding n ₈ is a connection point of a full-wave rectifier DB and a diode D ₁ Leakage transformer LT connected to
₁ and one end of the primary winding n _{8 of the} leakage transformer LT ₁
And the other end is MOSFET
Q _1, a capacitor C ₁₃ of the DC blocking connected between the connection point of Q _2, leakage transformer T ₁ of the secondary winding a load connected to n ₉ circuit 1 ₃ which from the power conversion circuit 10
Is configured.

[0040] Here, the load circuit 1 _3, a leakage transformer LT ₁ of the discharge lamp La ₁ to the power supply side terminal of the filament f ₁ is connected to one end of the secondary winding n _9, the power of one of the filaments f ₃ with a side terminal is connected to the power supply side terminal of the filament f ₂ of the discharge lamp La _1, discharge source-side terminal of the other filament f ₄ is connected to the other end of the secondary winding n ₉ leakage transformer LT ₁ a lamp La _2, the discharge lamp and capacitor C ₆ connected between the non-power supply side terminal of both filaments f _1, f ₂ of La _1, between non-power supply side terminal of the discharge lamp both filaments of La ₂ f _3, f ₄ consists capacitors connected C ₇ Prefecture, the leakage transformer LT ₁
A resonance circuit is composed of the capacitors C ₆ and C ₇ , and two discharge lamps La ₁ and La ₂ are connected in series. Since the filter circuit LPF is inserted between the AC power supply Vs and the full-wave rectifier DB, the input current has a substantially sinusoidal waveform with reduced harmonic components.

The operation of this circuit will be briefly described below.
I do. The basic operation of this circuit is almost the same as that of the circuit shown in FIG.
The same, the capacitor C₁₂Voltage V_C12The high frequency
Circuit that improves input distortion by vibrating
You. Here, the following two paths are used for the input current to flow.
There is a path, from AC power supply Vs to filter circuit LPF → all
Wave rectifier DB → leakage transformer LT₁Primary winding n
₈→ Capacitor C₁₃→ MOSFET Q_Two→ Full-wave rectifier D
B → Filter circuit LPF → AC power supply Vs path and AC
From power supply Vs, filter circuit LPF → full wave rectifier DB →
-Cage Transformer LT₁Primary winding n₈→ Capacitor C
₁₃→ MOSFET Q₁→ Smoothing capacitor C ₁→ Full-wave rectification
From the filter DB → filter circuit LPF → AC power supply Vs
Input current is drawn.

As described above, the input current is controlled by the leakage transformer LT ₁ , the capacitors C ₆ and C ₇ and the discharge lamps La ₁ and L
Since the flow through the configured load circuit 1 ₃ a _2, similarly to Embodiment 1, the input current depending on the resonance current flowing to the discharge lamp La _1, La ₂ is drawn by the input distortion improving operation. Therefore, depending on the characteristics of the discharge lamp one of the discharge lamps the previously preheating, by starting, the voltage across V _C1 of the smoothing capacitor C ₁ at the time of the discharge lamp start-up can be reduced to boost.

Incidentally, in this circuit is used leakage transformer LT ₁ to the load circuit 1 _3, a leakage transformer L
Since the resonance circuit is constituted by T ₁ and the capacitors C ₆ and C ₇ , the inductors L ₁ and L ₂ can be omitted and the number of parts can be reduced as compared with the discharge lamp lighting devices of the first to third embodiments. be able to. (Embodiment 4) FIG. 10 is a circuit diagram of a discharge lamp lighting device according to this embodiment. The operation of the power conversion circuit 10 at the time of starting the discharge lamp is the same as in the first embodiment, and a description thereof will be omitted.

In this circuit, the smoothing function as the first capacitor
Capacitor C₁And the smoothing capacitor C₁Connect between both ends of
First and second switches that alternately turn on and off at the high frequency
MOSFET Q as the switching element₁, Q_TwoSeries circuit
And the smoothing capacitor C₁A third connected between both ends of the
Diode D as fourth rectifying element_Three, D_FourSeries circuit
And the primary winding n_Ten, N₁₂One end of MOSFET Q₁, Q
_TwoAnd the primary winding n_Ten, N₁₂
Is connected via a filter circuit LPF and an AC power supply Vs
Diode D_Three, D_FourLeakage connected to a connection point
Trans LT_Two, LT_ThreeAnd leakage transformer L
T_Two, LT_ThreeSecondary winding n₁₁, N₁₃Negative connected to
Load circuit 1₁, 1_TwoAnd leakage transformer LT_Two, LT
_ThreePrimary winding n _Ten, N₁₂And filter circuit LPF connection
One end is connected to the point and the diode D_FourAnd M
OSFETQ_TwoWith the other end connected to the connection point of
C₁₃Thus, the power conversion circuit 10 is configured. In addition, MOS
FETQ₁, Q_TwoParasitic diode (not shown)
First and second rectifying elements are configured.

Here, the load circuit 1₁Is a leakage tiger
Lance LT_TwoSecondary winding n₁₁In parallel with both filaments
Discharge lamp La to which the source terminal is connected₁And the discharge lamp La₁of
A fifth core connected between the non-power supply terminals of both filaments
Capacitor C₆Is composed of
Zitrans LT_TwoAnd capacitor C₆From the resonance circuit
Is done. Also, load circuit 1_TwoIs a leakage transformer
LT_ThreeSecondary winding n₁₃Power supply side of both filaments in parallel with
Discharge lamp La with terminal connected_TwoAnd the discharge lamp La _TwoBoth
The fifth capacitor connected between the non-power supply terminals of the
Capacitor C₇And a leaked
Lance LT_ThreeAnd capacitor C₇From the resonant circuit
It is. The load circuit 1₁, 1_TwoIs the discharge lamp La₁, La
_TwoAre connected in parallel with each other.

The operation of this circuit will be briefly described below.
This circuit uses a capacitor C₁₃Voltage V_C13The high frequency
Circuit that improves input distortion by vibrating
You. Here, the following four paths
There is a route. The polarity of the AC power supply Vs is set in the direction of the arrow in FIG.
When the power supply voltage of the AC power supply Vs is positive,
From the AC power supply Vs to the filter circuit LPF → diode
D_Three→ MOSFET Q₁→ Leakage transformer LT₁,
LT_TwoPrimary winding n_Ten, N₁₂→ Filter circuit LPF → Interchange
From the AC power supply Vs to the path of the
PF → Diode D _Three→ Smoothing capacitor C₁→ MOSF
ETQ_Two→ Leakage transformer LT₁, LT _TwoPrimary volume
Line n_Ten, N₁₂→ Filter circuit LPF → AC power supply Vs
The input current is drawn by the path. On the other hand, the AC power supply Vs
In the region where the power supply voltage is negative, the filter circuit is switched from the AC power supply Vs.
Road LPF → leakage transformer LT₁, LT_TwoPrimary volume
Line n_Ten, N₁₂→ MOSFET Q_Two→ Diode D_Four→ F
Filter circuit LPF → AC power supply Vs path and AC power supply Vs
s to filter circuit LPF → leakage transformer L
T₁, LT_TwoPrimary winding n_Ten, N₁₂→ MOSFET Q₁
→ Smoothing capacitor C₁→ Diode D_Four→ Filter circuit
Input current is drawn in the path from LPF to AC power supply Vs
You. Thus, the input current is₁, 1_TwoThrough
As in the first embodiment, the flow
The input current that depends on the vibration current is drawn by the input distortion improvement operation.
I will be absorbed. Therefore, the discharge lamp La₁, La_TwoCharacteristics of
Depending on the preheating of one of the two lamps first,
As in the case of the first embodiment,
Smoothing capacitor C₁Voltage V_C1Reduce boost
Can be

In this embodiment, two discharge lamps La ₁ ,
Although La ₂ is turned on, the number of discharge lamps is not limited to two, and needless to say, three or more discharge lamps may be provided. (Embodiment 5) A circuit diagram of the discharge lamp lighting device of the present embodiment is shown in FIG. The operation of the power conversion circuit 10 at the time of starting the discharge lamp is the same as in the first embodiment, and a description thereof will be omitted.

In this circuit, a full-wave rectifier D that performs full-wave rectification on the AC power supply Vs input through the filter circuit LPF
B and a smoothing capacitor C ₁ as a first capacitor having one end connected to the low potential side of the DC output terminal of the full-wave rectifier DB.
And a series circuit of MOSFETs Q ₁ and Q ₂ as first and second switching elements, which are alternately turned on and off at a high frequency, connected between both ends of the smoothing capacitor C ₁ , and a DC output terminal of the full-wave rectifier DB. a fourth capacitor serving capacitor C ₁₅ connected, full-wave rectifier leakage transformer LT primary winding n ₁₄ is connected between the high potential side and the MOSFET Q _1, connection point Q ₂ 'of the DC output terminals of the DB _4, the power converter circuit 10 from the connected load circuit 1 ₄ which across the secondary winding n ₁₅ of the leakage transformer LT ₄ is formed. The first and second rectifying elements are constituted by parasitic diodes (not shown) of the MOSFETs Q ₁ and Q ₂ .

[0049] Here, the load circuit 1 _4, a leakage transformer LT _4, and the balancer coil T ₄ to equalize the lamp current flowing through the discharge lamp La _1, La ₂ described later, both filaments through the balancer coil T ₄ And the discharge lamps La ₁ and La ₂ having the secondary winding n ₁₅ of the leakage transformer LT ₄ connected between the power supply side terminals thereof, and the non-power supply side terminals of both filaments of the discharge lamps La ₁ and La _2. and and a fifth capacitor serving capacitor C _6, C ₇ Prefecture.

[0050] This circuit voltage V across the capacitor C _15
The input distortion is improved by vibrating _C15 at high frequency, and the primary winding n _{14 of the} filter circuit LPF → the full-wave rectifier DB → the leakage transformer LT ₄ is improved from the AC power supply Vs.
→ MOSFET Q ₂ → Full-wave rectifier DB → Filter circuit L
PF → AC power supply Vs path and AC power supply Vs to filter circuit LPF → Full-wave rectifier DB → Leakage transformer L
Input current drawn by the primary winding n ₁₄ → MOSFETQ ₁ → smoothing capacitor C ₁ → the full-wave rectifier DB → filter circuit T ₄ LPF → path of the AC power source Vs. In this circuit this way, as in the first embodiment, since the input current depending on the resonance current flowing through the load circuit 1 ₄ is drawn by the input distortion improving operation, either in accordance with the characteristics of the discharge lamp La _1, La ₂ By preheating and starting one of the discharge lamps first, it is possible to reduce the increase in the voltage V _C1 across the smoothing capacitor C ₁ at the time of starting.

[0051] Incidentally, the configuration of the load circuit 1 ₄ is not intended to limit to the above configuration, it is of course the load circuit 1 ₄ may be other configurations. For example, the step-up ratio of the leakage transformer LT ₄ is 1: 1, as shown in FIG. 11 (b), the high potential side and the MOSFET Q _1, the connection point Q ₂ 'of the DC output ends of the full-wave rectifier DB the inductor L ₃ is inserted between, across the inductor L ₃ through the inductor L ₄ and the balancer coil T ₄ the discharge lamp L
a ₁ and La ₂ are connected to the power supply side terminals of both filaments,
By connecting a capacitor C _6, C ₇ between the discharge lamp La _1, La ₂ of non-power-side terminals of both filaments may constitute a load circuit 1 _4.

[0052]

As described above, according to the first aspect of the present invention, a DC voltage obtained by rectifying and smoothing an AC power supply is converted into a high frequency and applied to a load circuit including a plurality of discharge lamps via a transformer or an inductor. A power conversion circuit that supplies high-frequency power and draws an input current corresponding to a resonance current flowing through the discharge lamp is provided. The power conversion circuit first starts at least one discharge lamp, and then varies an operating frequency. Since the remaining discharge lamps are started, an input current corresponding to the resonance current flowing through one discharge lamp is drawn at the time of starting, which is an input current that is drawn compared to a case where a plurality of discharge lamps are started at the same time. This has the effect of reducing the current and reducing the step-up of the DC voltage obtained by rectifying and smoothing. Further, at the time of starting the second and subsequent lamps, since there is a discharge lamp that has already been started, power is consumed by the discharge lamp, so that there is an effect that the boosting of the DC voltage obtained by rectifying and smoothing can be further reduced.

According to a second aspect of the present invention, in the power conversion circuit, the discharge lamp having a small resonance current flowing through the load circuit is first started, and then the remaining discharge lamps are started by changing the operating frequency. Here, since the input current according to the resonance current flowing through the discharge lamp is drawn in, the discharge current having a small resonance current is first started, so that the input current at the time of starting is reduced, and the rectified and smoothed DC voltage is obtained. There is an effect that the boost can be further reduced.

According to a third aspect of the present invention, the power conversion circuit starts the discharge lamp having a high rated power first, and then starts the remaining discharge lamps by changing the operating frequency. Since the no-load resonance frequency of the discharge lamp is higher than that of the other discharge lamps and close to the resonance point at the time of rated lighting, the output power can be increased and the rated power can be secured.

According to a fourth aspect of the present invention, in the power conversion circuit, the discharge lamp having a large applied start voltage is first started, and then the remaining discharge lamps are started by changing the operating frequency. Here, when starting the second and subsequent discharge lamps,
Since the first discharge lamp has already been started, it is possible to reduce the step-up of the DC voltage obtained by rectifying and smoothing, but it is difficult to secure a starting applied voltage for the second and subsequent discharge lamps. Therefore, starting the discharge lamp with a high applied start voltage first has an effect that the discharge lamp can be started reliably.

According to a fifth aspect of the present invention, in the power conversion circuit, the discharge lamp having the large preheating current is first started, and then the remaining discharge lamps are started by changing the operating frequency. Here, if the starting applied voltage is set to a certain voltage or less, the higher the operating frequency, the higher the preheating current, so starting the discharge lamp with the higher preheating current first sufficiently reduces the preheating current. There is an effect that it can be secured.

According to a sixth aspect of the present invention, the power conversion circuit includes a full-wave rectifier for full-wave rectification of the AC power supply and a first smoothing rectifier connected via a diode between the DC output terminals of the full-wave rectifier.
, A second capacitor connected in parallel with the diode, first and second switching elements that are alternately turned on and off and connected between both ends of the first capacitor; First and second rectifier elements respectively connected in antiparallel with the switching element, and connected between a DC output terminal of the full-wave rectifier and a connection point of the diode and a connection point of the first and second switching elements. 8. The power conversion system according to claim 7, further comprising: a series circuit including a primary winding of a transformer and a third capacitor; and a load circuit including a plurality of discharge lamps connected to a secondary winding of the transformer. The circuit includes a full-wave rectifier for full-wave rectification of an AC power supply, a first capacitor for smoothing having one end connected to a low potential side of a DC output terminal of the full-wave rectifier, and a circuit connected between both ends of the first capacitor. Was alternately A series circuit of off to the first and second switching elements, first and second rectifying elements are first and second switching elements and respectively connected in antiparallel,
A fourth capacitor connected between the DC output terminals of the full-wave rectifier, and a primary winding between a connection point between the high potential side of the DC output terminal of the full-wave rectifier and the first and second switching elements. It is composed of a connected transformer and a load circuit including a plurality of discharge lamps connected to the secondary winding of the transformer,
In a preferred embodiment of the present invention, the power conversion circuit comprises a first capacitor for smoothing, first and second switching elements connected between both ends of the first capacitor, which are alternately turned on and off, and A first and a second rectifying element connected in anti-parallel with the second and the second switching element, a third and a fourth rectifying element connected between both ends of the first capacitor, and one end of the primary winding. A transformer connected to a connection point of the first and second switching elements and having the other end of the primary winding connected to a connection point of the third and fourth rectifier elements via an AC power supply; And a load circuit including a plurality of discharge lamps connected between both ends of the next winding. Therefore, similarly to the first embodiment, the input current corresponding to the resonance current flowing through one discharge lamp at the time of starting is similar to the first embodiment. Will be drawn in, and multiple discharge lamps will be Input current is reduced to be drawn in comparison to the case of moving, there is an effect of reducing the boosted DC voltage obtained by rectifying and smoothing. Also, when starting the second and subsequent lamps, there is a discharge lamp that has already started,
Since power is consumed by the discharge lamp, there is an effect that the boosting of the DC voltage obtained by rectifying and smoothing can be further reduced.

According to a ninth aspect of the present invention, the load circuit comprises at least a resonance inductor, a fifth resonance capacitor, and a discharge lamp.
The discharge lamp comprises a fluorescent lamp, a fifth capacitor is connected between the non-power-supply-side terminals of the filament at both ends of the fluorescent lamp,
One end of the inductor is connected to the power supply terminal of one filament of the fluorescent lamp, and the secondary winding of the transformer is connected between the power supply terminal of the other filament of the fluorescent lamp and the other end of the inductor. Therefore, the DC voltage obtained by rectifying and smoothing is reduced, and the fluorescent lamp can be reliably turned on.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a discharge lamp lighting device according to a first embodiment.

FIG. 2 is a diagram showing a resonance curve according to the first embodiment;

FIG. 3 is a diagram showing a resonance curve when a discharge lamp having a small resonance current is turned on first at the time of starting the lamp.

FIG. 4 is a diagram showing a resonance curve when a discharge lamp having a large rated output is turned on first.

FIG. 5 is a circuit diagram showing a circuit configuration using another preheating method according to the first embodiment.

FIG. 6 is a circuit diagram showing a circuit configuration using another preheating method according to the first embodiment;

FIG. 7 is a circuit diagram showing a circuit configuration in which n sets of load circuits are connected.

FIG. 8 is a circuit diagram illustrating a discharge lamp lighting device according to a second embodiment.

FIG. 9 is a circuit diagram illustrating a discharge lamp lighting device according to a third embodiment.

FIG. 10 is a circuit diagram showing a discharge lamp lighting device according to a fourth embodiment.

FIG. 11A is a circuit diagram illustrating a discharge lamp lighting device according to a fifth embodiment, and FIG. 11B is a circuit diagram illustrating another load circuit according to the fifth embodiment, which is partially omitted.

FIG. 12 is a circuit diagram showing a conventional discharge lamp lighting device.

FIG. 13 is a diagram showing a resonance curve of the resonance circuit of the above.

[Explanation of symbols]

1 ₁ , 1 ₂ load circuit 10 power conversion circuit C ₁ smoothing capacitor Vs AC power supply La ₁ , La ₂ discharge lamp

Claims (10)

[Claims] A DC voltage obtained by rectifying and smoothing an AC power supply is converted into a high frequency, and a high frequency power is supplied to a load circuit including a plurality of discharge lamps via a transformer or an inductor, and a resonance flowing through the discharge lamp is supplied. A power conversion circuit for drawing an input current corresponding to the current, wherein the power conversion circuit first starts at least one discharge lamp, and then starts the remaining discharge lamps by varying an operating frequency. Discharge lamp lighting device. 2. The power conversion circuit according to claim 1, wherein the discharge lamp having a small resonance current flowing through the load circuit is started first, and then the remaining discharge lamps are started by changing the operating frequency. Discharge lamp lighting device. 3. The discharge lamp lighting device according to claim 1, wherein the power conversion circuit starts the discharge lamp having a large rated power first, and then starts the remaining discharge lamps by changing an operation frequency. apparatus. 4. The discharge lamp according to claim 1, wherein the power conversion circuit starts the discharge lamp having a high applied start voltage, and then starts the remaining discharge lamps by changing the operating frequency. Lighting device. 5. The discharge lamp according to claim 1, wherein the power conversion circuit starts the discharge lamp having a large preheating current first, and then starts the remaining discharge lamps by changing the operating frequency. Lighting device. 6. A full-wave rectifier for full-wave rectifying an AC power supply, a first capacitor for smoothing connected via a diode between DC output terminals of the full-wave rectifier, and a power conversion circuit in parallel with the diode. A second capacitor connected to
First and second switching elements connected between both ends of the first and second capacitors, and first and second switching elements connected in anti-parallel with the first and second switching elements, respectively.
And a series circuit comprising a primary winding of a transformer and a third capacitor connected between a connection point of a DC output terminal and a diode of the full-wave rectifier and a connection point of the first and second switching elements. 6. The discharge lamp lighting device according to claim 1, further comprising a load circuit including a plurality of discharge lamps connected to a secondary winding of the transformer. 7. A full-wave rectifier for full-wave rectifying an AC power supply, a first capacitor for smoothing having one end connected to a low potential side of a DC output terminal of the full-wave rectifier, And a series circuit of first and second switching elements that are alternately turned on and off and connected between both ends of the first capacitor, and a first circuit that is connected in anti-parallel to the first and second switching elements, respectively.
And a second capacitor connected between the DC output terminals of the full-wave rectifier, and a connection point between the high potential side of the DC output terminal of the full-wave rectifier and the first and second switching elements. 6. A discharger according to claim 1, further comprising a transformer having a primary winding connected between the transformer and a load circuit including a plurality of discharge lamps connected to a secondary winding of the transformer. Lighting device. 8. A power conversion circuit comprising: a first capacitor for smoothing; first and second switching elements that are connected between both ends of the first capacitor and that are turned on and off alternately;
A first and a second rectifying element connected in anti-parallel with the second and the second switching element, a third and a fourth rectifying element connected between both ends of the first capacitor, and one end of the primary winding. A transformer connected to a connection point of the first and second switching elements and having the other end of the primary winding connected to a connection point of the third and fourth rectifier elements via an AC power supply; 6. The discharge lamp lighting device according to claim 1, further comprising a load circuit including a plurality of discharge lamps connected between both ends of the next winding. 9. The discharge lamp lighting device according to claim 6, wherein said load circuit comprises at least a resonance inductor, a fifth resonance capacitor, and a discharge lamp. 10. The discharge lamp comprises a fluorescent lamp, a fifth capacitor is connected between the non-power supply side terminals of the filaments at both ends of the fluorescent lamp, and one end of an inductor is connected to the power supply side terminal of one filament of the fluorescent lamp. The discharge lamp lighting device according to claim 9, wherein a secondary winding of the transformer is connected between the power supply terminal of the other filament of the fluorescent lamp and the other end of the inductor.