JP2001157467A - Power source system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source system capable of suppressing a stress to a circuit component due to a decrease in the impedance of a load at a low temperature. SOLUTION: Four diodes D1 to D4 for constituting a rectifier DB, a drive transformer CT, switching elements Q1, Q2, and a leakage transformer T2 of a load circuit 1 are sequentially arranged in this order in a lengthwise direction on a printed board 30. The transformer CT is arranged on a straight line for connecting both the elements Q1, Q2 in the widthwise direction of the board 30. Since the transformer CT is heated by radiant heats of the diodes D1 to D4, the elements Q1, Q2 and the transformer T2 even when the power is applied and the impedance of a discharge lamp La is low at a low temperature so that a saturated magnetic flux density is lowered, turning off of the elements Q1, Q2 is fastened, and hence the operating frequency is transferred to the operating frequency at the normal operation time in a relatively short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device using an inverter circuit.

[0002]

2. Description of the Related Art Conventionally, a power supply device having a circuit configuration shown in FIG. 14 has been proposed. The power supply device having the circuit configuration shown in FIG. 14 employs a configuration in which DC power obtained by rectifying an AC power supply Vs such as a commercial power supply is converted into high-frequency power by an inverter circuit INV and supplied to a load La. .

The AC power supply Vs is input to a rectifier circuit DB via a high frequency blocking filter circuit F to be full-wave rectified. The rectifier circuit DB has four diodes D
1 to D4. The filter circuit F is provided to prevent a high-frequency current from leaking from the inverter circuit INV to the AC power supply Vs.

[0004] A capacitor C2 is connected between the DC output terminals of the rectifier circuit DB, and an inverter circuit INV is connected.

[0005] The inverter circuit INV includes a series circuit of a pair of switching elements Q1 and Q2 composed of MOSFETs connected between a DC output terminal of a rectifier circuit DB via a series circuit in which two diodes D5 and D6 are connected in series in the forward direction. It is connected to the. A smoothing capacitor C0 is connected in parallel to a series circuit of both switching elements Q1 and Q2, and a diode D
Reference numeral 6 denotes a resonance capacitor C4 which is an impedance element.
Are connected in parallel. A series circuit of a DC cut capacitor C3, a load circuit 1, and a drive transformer CT is connected between a connection point of the diodes D5 and D6 and a connection point of the switching elements Q1 and Q2.

The load circuit 1 includes a leakage transformer T2 having a primary winding connected between a DC cut capacitor C3 and a driving transformer CT, and a load La connected between secondary windings of the leakage transformer T2. And a resonance capacitor C5 connected in parallel to the load La. Here, a discharge lamp is used as the load La, and the filament of the discharge lamp La is not shown in FIG. ing. The capacitor C5 forms an LC resonance circuit together with the leakage inductance of the leakage transformer T2.

The drive transformer CT has a primary winding n1 of the drive transformer CT connected between a connection point of the two switching elements Q1 and Q2 and a primary winding of the leakage transformer T2, and is provided on the drive transformer CT. Two secondary windings n2
1, n22, a series circuit of a secondary winding n21 and a gate resistor R1 is connected between the gate and source of the switching element Q1, and a series circuit of the other secondary winding n22 and a gate resistor R2 is connected to a switching element. It is connected between the gate and source of Q2. Therefore, the drive transformer CT becomes a means for self-exciting the switching elements Q1 and Q2, and the switching elements Q1 and Q2 are turned on and off alternately at a high frequency.

Hereinafter, the operation of the circuit shown in FIG. 14 will be briefly described.

Now, assuming that a steady operation is performed, the switching element Q1 and the switching element Q2 are alternately turned on and off. In the latter half of the period when the switching element Q2 is on, the smoothing capacitor C0 is used as a power source by using the smoothing capacitor C0 as a power supply. -Capacitor C4-Capacitor C3-
A resonance current flows through the load circuit 1 through the load circuit 1-the primary winding n of the driving transformer CT 1-the switching element Q2-the smoothing capacitor C0, and the voltage obtained by adding the voltage across the capacitor C4 to the output voltage of the rectifier circuit DB. Smoothing capacitor C
0, the AC power supply Vs-rectifier circuit D
B-diode D5-capacitor C3-load circuit 1-primary winding n of drive transformer CT1-switching element Q2
The resonance current flows through the path of the rectifier circuit DB-AC power supply Vs (at this time, the input current is drawn from the AC power supply Vs, and the current value of the input current becomes a value proportional to the instantaneous value of the AC power supply Vs).

Next, when the switching element Q2 is turned off, a regenerative current from the leakage transformer T2 of the load circuit 1 is applied to the leakage transformer T2-the driving transformer CT.
Next winding n1-parasitic diode of switching element Q1-
The current flows through the path of the smoothing capacitor C0, the rectifier circuit DB, the AC power supply Vs, the rectifier circuit DB, the diode D5, the capacitor C3, and the leakage transformer T2.
s, the input current is drawn, and the current value of the input current becomes a value proportional to the instantaneous value of the AC power supply Vs).

Thereafter, when the regenerative current of the leakage transformer T2 becomes zero, the capacitors C3 to C3
-A capacitor C4-a switching element Q1-a primary winding n of the driving transformer CT-a load circuit 1-a resonance current flows through the load circuit 1 through the path of the capacitor C3, and a charge stored in the capacitor C4 when the switching element Q2 is turned on. When the charge of the capacitor C4 becomes zero, the resonance current flows from the capacitor C3 to the load circuit 1 through the path of the capacitor C3, the diode D6, the switching element Q1, the primary winding n of the drive transformer CT, the load circuit 1 and the capacitor C3. Flows.

Next, when the switching element Q2 is turned on, the regenerative current of the leakage transformer T2 of the load circuit 1 is changed to the leakage transformer T2-capacitor C3-diode D6-smoothing capacitor C0-switching element Q2.
Of the primary winding n1- of the driving diode CT
It flows on the path of the leakage transformer T2. Thus, when the electromagnetic energy of the leakage transformer T2 is released,
Again, the resonance current flows through the load circuit 1 using the smoothing capacitor C0 as a power supply, and the above operation is repeated.

By repeating these series of operations, high-frequency power is supplied to the discharge lamp La. By the way, in the circuit configuration shown in FIG. 14, since the filter circuit F for blocking high frequency is provided, the current input through the filter circuit F has a sinusoidal waveform substantially proportional to the voltage of the AC power supply Vs, A current distortion is small and a relatively high input power factor can be obtained. Further, since the regenerative current of the leakage transformer T2 is used for charging the smoothing capacitor C0, a stable power supply for the inverter circuit INV can be secured.

Incidentally, a power supply device having a configuration shown in FIG. 15 is also known. The basic configuration of the power supply device shown in FIG. 15 is substantially the same as the configuration shown in FIG. 14. In the configuration shown in FIG. 14, a smoothing capacitor C0 is connected in parallel to a series circuit of two switching elements Q1 and Q2. However, the difference is that a series circuit of a smoothing capacitor C0 and a diode D8 is connected in parallel to a series circuit of the two switching elements Q1 and Q2, and a capacitor C6 is connected in parallel. Here, the diode D8 has an anode connected to the DC output terminal on the negative side of the rectifier circuit DB,
The cathode is connected to the smoothing capacitor C0 to form a discharge path for the smoothing capacitor C0. Further, a diode D7 is connected between a connection point between the smoothing capacitor C0 and the diode D8 and a connection point between the capacitor C3 and the leakage transformer T2. Here, diode D7
Has an anode connected to the cathode of diode D8,
The cathode is connected to a connection point between the capacitor C3 and the leakage transformer T2. The circuit 2 including the smoothing capacitor C0, the diodes D7 and D8, and the capacitor C6 smoothes the voltage applied to the series circuit of the switching elements Q1 and Q2 only during a part of the output voltage of the rectifier circuit DB. Circuit (or power supply circuit)
is called.

The operation of the circuit shown in FIG. 15 will be briefly described below.

Assuming that a steady operation is performed, the switching element Q1 and the switching element Q2 are alternately turned on and off, and in the latter half of the period when the switching element Q2 is on, the partial smoothing circuit 2-capacitor C4-
A resonance current flows through the load circuit 1 through a path of the capacitor C3-the load circuit 1-the primary winding n of the drive transformer CT 1-the switching element Q2-the partial smoothing circuit 2, and the voltage across the capacitor C4 is output to the rectifier circuit DB. When the added voltage balances the voltage between both ends of the partial smoothing circuit 2, the AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-load circuit 1-primary winding n of drive transformer CT1-switching element Q2-rectifier circuit DB A resonance current flows through the load circuit 1 through the path of the AC power supply Vs (in this case, the input current is drawn from the AC power supply Vs, and the current value of the input current is
s) is proportional to the instantaneous value of s).

Next, when the switching element Q2 is turned off, the regenerative current from the leakage transformer T2 of the load circuit 1 is applied to the leakage transformer T2-the driving transformer CT.
Next winding n1-parasitic diode of switching element Q1-
The current flows through the path of the partial smoothing circuit 2-rectifier circuit DB-AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-leakage transformer T2. (Also at this time, the input current is drawn from the AC power supply Vs. The value is proportional to the instantaneous value of the AC power supply Vs).

Thereafter, when the regenerative current of the leakage transformer T2 becomes zero, the capacitors C3 to C3
-A capacitor C4-a switching element Q1-a primary winding n of the driving transformer CT-a load circuit 1-a resonance current flows through the load circuit 1 through the path of the capacitor C3, and a charge stored in the capacitor C4 when the switching element Q2 is turned on. When the charge of the capacitor C4 becomes zero, the resonance current flows from the capacitor C3 to the load circuit 1 through the path of the capacitor C3, the diode D6, the switching element Q1, the primary winding n of the drive transformer CT, the load circuit 1 and the capacitor C3. Flows.

Next, when the switching element Q2 is turned on, the regenerative current of the leakage transformer T2 of the load circuit 1 is changed to a leakage transformer T2-capacitor C3-diode D6-partial smoothing circuit 2-parasitic diode of the switching element Q2-drive transformer CT A regenerative current flows through the path of the primary winding n1-leakage transformer T2.

By repeating these series of operations, high-frequency power is supplied to the discharge lamp La. by the way,
Also in the circuit configuration shown in FIG. 15, since the filter circuit F for blocking high frequency is provided, the current input through the filter circuit F has a sinusoidal waveform substantially proportional to the voltage of the AC power supply Vs, and the harmonic current It is possible to obtain a relatively high input power factor with little distortion. Further, since the regenerative current of the leakage transformer T2 is used for charging the smoothing capacitor C0 of the partial smoothing circuit 2, a stable power supply for the inverter circuit INV can be secured.

The on / off operation of the switching elements Q1 and Q2 causes the smoothing capacitor C0 of the partial smoothing circuit 2 to operate.
Is charged via the leakage transformer T2 and the primary winding n1 of the drive transformer CT, and is smoothed at a value lower than the peak voltage of the output voltage of the rectifier circuit DB.

[0022]

By the way, in each of the circuit configurations shown in FIGS. 14 and 15, a discharge lamp is used as the load La. However, a general fluorescent lamp uses a rare gas such as mercury and argon in a glass tube. Gas is enclosed. For this reason,
The characteristics of a fluorescent lamp are mainly determined by the vapor pressure of mercury in the glass tube, and the vapor pressure of the mercury has a large ambient temperature dependency. Designed to be maximum.

For this reason, in the above-described conventional configuration, when the impedance of the discharge lamp La at normal temperature is defined as the rated impedance, the impedance of the discharge lamp La becomes lower than the rated impedance at a low temperature. Since the impedance becomes small, when the two switching elements Q1 and Q2 operate at the same frequency,
The resonance current will increase. Here, the resonance current flows through the path passing through the primary winding n1 of the drive transformer CT as described above.

On the other hand, although the drive transformer CT has only a very small inductance value which hardly affects the load circuit 1, the drive transformer CT has an increased resonance current.
The amplitude of the pulse voltage generated in each of the secondary windings n21 and n22 increases (that is, the switching element Q
1, the amplitude of the drive signal of Q2 increases), so that the operating frequency of switching elements Q1 and Q2 decreases, and as a result, the period during which smoothing capacitor C0 is charged becomes longer, and the charge amount of smoothing capacitor C0 increases. In addition, the discharge lamp L
When the impedance of a becomes low, the switching element Q
Discharge lamp La due to the lowering of the operating frequency of Q1,
Although the power consumption of the discharge lamp La increases, the power consumption of the discharge lamp La at the predetermined temperature is smaller than that of the discharge lamp La. Therefore, surplus energy is used for charging the smoothing capacitor C0, and the voltage across the smoothing capacitor C0 increases. However, the inflow of the input current also increases. Then, the inverter circuit INV
, The power supplied to the discharge lamp La further increases, and the impedance of the discharge lamp La further decreases. From these series of operating characteristics, the inverter circuit I
An increase in the power supply voltage of the NV, an increase in the input current, a reduction in the operating frequency of the switching elements Q1 and Q2, and an increase in power consumption cause excessive stress on the elements (circuit components) constituting the power supply device. There was a problem of getting it.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply device capable of suppressing stress on circuit components due to a decrease in load impedance at a low temperature. is there.

[0026]

According to a first aspect of the present invention, there is provided a rectifier including a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements alternately turned on and off at a high frequency. Inverter circuit that converts DC power to high-frequency power on the DC output side of the circuit and supplies the load with high-frequency power, a smoothing capacitor connected in parallel to the series circuit of the two switching elements, and a rectifier circuit and an inverter circuit. A rectangular printed circuit board on which components are mounted, wherein the inverter circuit is a drive transformer for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit. And a series circuit composed of a load circuit including the LC resonance circuit and the load and a DC cut capacitor, and connected to the printed circuit board. The rectifier circuit, the drive transformer, each switching element, and the inductance element of the load circuit are arranged in this order from the input side at one end to the output side at the other end in the longitudinal direction. It is characterized by being arranged on a straight line connecting the switching elements, and even if power is turned on at low temperature and the impedance of the load is low, radiant heat of the rectifier circuit, each switching element, inductance element etc. Since the drive transformer is heated and the saturation magnetic flux density of the drive transformer decreases, the turn-off of each switching element is advanced, and the operating frequency of each switching element shifts to the operating frequency at the time of steady operation in a relatively short time, Stress on circuit components due to lower load impedance at low temperatures It can be obtained.

According to a second aspect of the present invention, there is provided a rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements alternately turned on and off at a high frequency. An inverter circuit for supplying high-frequency power to a load, a smoothing capacitor connected in parallel to the series circuit of the two switching elements, and a rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted. An inverter circuit includes a driving transformer and an LC resonance circuit for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit, and a load circuit including the load and a DC cut. And a printed circuit board is connected from the input side at one end in the longitudinal direction to the output side at the other end. , A rectifier circuit, a drive transformer and each switching element, and an inductance element of the load circuit are arranged in this order, and the drive transformer is arranged substantially at the center in the width direction of the printed circuit board, and both switching elements are arranged in the width direction of the printed circuit board. It is characterized by being arranged at one end side, even if the power is turned on at low temperature and the impedance of the load is low, the rectifier circuit,
Since the drive transformer is heated by radiant heat of each switching element, inductance element, etc., and the saturation magnetic flux density of the drive transformer decreases, the turn-off of each switching element is accelerated, and the operating frequency of each switching element is set to a steady operation in a relatively short time. The operating frequency is shifted to the above, and the stress on the circuit components due to the decrease in the impedance of the load at the time of low temperature can be suppressed.

A third aspect of the present invention includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements which are alternately turned on and off at a high frequency. And an inverter circuit for supplying high-frequency power to the load, and a smoothing capacitor, which is connected in parallel to the series circuit of the two switching elements and is applied to the series circuit of the two switching elements only during a partial period of the output voltage of the rectifier circuit. And a rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted. The inverter circuit includes a connection point between the two switching elements and one of the direct currents of the rectifier circuit. A drive transformer for self-exciting control of the two switching elements, an LC resonance circuit, and a negative A series circuit composed of a circuit and a DC cut capacitor is connected, and the printed circuit board includes a rectifier circuit, a drive transformer, each switching element, and an inductance of a load circuit from the input side at one end to the output side at the other end. And a drive transformer is arranged on a straight line connecting the two switching elements in the width direction of the printed circuit board. Even if the impedance is low, the drive transformer is heated by radiation heat of the rectifier circuit, each switching element, the inductance element, etc., and the saturation magnetic flux density of the drive transformer is reduced. The operating frequency of the switching element shifts to the operating frequency during normal operation. , It is possible to suppress the stress on the circuit components due to a decrease in the impedance of the load at low temperatures.

A fourth aspect of the present invention includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements that are alternately turned on and off at a high frequency. And an inverter circuit for supplying high-frequency power to the load, and a smoothing capacitor, which is connected in parallel to the series circuit of the two switching elements and is applied to the series circuit of the two switching elements only during a partial period of the output voltage of the rectifier circuit. And a rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted. The inverter circuit includes a connection point between the two switching elements and one of the direct currents of the rectifier circuit. A driving transformer for self-exciting control of the switching elements and an LC resonance circuit between the output terminal and the negative terminal including the load. A series circuit consisting of a circuit and a DC cut capacitor is connected, and the printed circuit board is provided with a rectifier circuit, a drive transformer, each switching element, and an inductance of a load circuit from the input side at one end to the output side at the other end. The driving transformer is disposed in the order of the elements, the driving transformer is disposed substantially at the center in the width direction of the printed circuit board, and both switching elements are disposed at one end side in the width direction of the printed circuit board. Even when the power is turned on at low temperature and the impedance of the load is low, the drive transformer is heated by the radiant heat of the rectifier circuit, each switching element, the inductance element, etc., and the saturation magnetic flux density of the drive transformer is reduced. The turn-off of the elements is accelerated, and the operating frequency of each switching element increases in a relatively short time. Will be migrated to the operating frequency during normal operation, it is possible to suppress stress on the circuit components due to a decrease in the impedance of the load at low temperatures.

The fifth aspect of the present invention includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements which are alternately turned on and off at a high frequency. And a smoothing capacitor connected in parallel to the series circuit of the two switching elements, wherein the inverter circuit includes a connection point between the two switching elements and one of the rectifier circuits. A drive transformer for self-exciting control of the two switching elements, a series circuit including an LC resonance circuit, a load circuit including the load, and a DC cut capacitor are connected between the drive transformer and the DC output terminal. A primary winding connected between the connection point of the two switching elements and a load circuit; A wire is connected to each of the switching elements so as to alternately turn on and off the switching elements, and an impedance element having a positive characteristic with respect to temperature is connected in parallel to the primary winding. When the load is low and the impedance of the load is low at a low temperature, the ratio of the current flowing through the impedance element to the current flowing through the primary winding of the drive transformer becomes large, resulting in each secondary winding of the drive transformer. Since the amplitude of the pulse voltage generated in the line decreases and the oscillation frequency of each switching element increases, it is possible to suppress the stress on the circuit components caused by the decrease in the load impedance at low temperatures.

According to a sixth aspect of the present invention, there is provided a rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements alternately turned on and off at a high frequency. The DC output side of the rectifier circuit converts DC power into high-frequency power. An inverter circuit that supplies high-frequency power to the load, and a voltage that includes a smoothing capacitor and is connected in parallel to the series circuit of the two switching elements and is applied to the series circuit of both switching elements only during a part of the output voltage of the rectifier circuit. A drive transformer for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit, and an LC resonance circuit. A series circuit including a circuit and a load circuit including the load and a DC cut capacitor is connected, and the drive transformer is A primary winding connected between a connection point of the two switching elements and a load circuit, and two secondary windings turning on and off the two switching elements alternately. And an impedance element having a positive characteristic with respect to temperature is connected in parallel to the primary winding. When the impedance is low, the ratio of the current flowing in the impedance element to the current flowing in the primary winding of the drive transformer increases, and as a result, the amplitude of the pulse voltage generated in each secondary winding of the drive transformer decreases, Since the oscillation frequency of each switching element increases,
It is possible to suppress stress on circuit components due to a decrease in load impedance at low temperatures.

According to a seventh aspect of the present invention, in the fifth or sixth aspect, the impedance element is a series circuit of a resistor and a temperature-sensitive element having a positive temperature coefficient. The influence of the impedance element can be prevented.

[0033] The invention of claim 8 includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements which are alternately turned on and off at a high frequency. The DC output side of the rectifier circuit converts DC power into high-frequency power. And a smoothing capacitor connected in parallel to the series circuit of the two switching elements, wherein the inverter circuit includes a connection point between the two switching elements and one of the rectifier circuits. A drive transformer for self-exciting control of the two switching elements, a series circuit including an LC resonance circuit, a load circuit including the load, and a DC cut capacitor are connected between the DC transformer and the DC output terminal. A primary winding connected between the connection point of the two switching elements and a load circuit; A line is connected to each of the switching elements so as to alternately turn on and off the switching elements, and two impedance elements each having a negative characteristic with respect to temperature are connected in series to each secondary winding. When the power is turned on at a low temperature and the impedance of the load is low, the impedance of the impedance element connected in series to each secondary winding of the drive transformer is large, and each secondary winding of the drive transformer is The amplitude of the pulse voltage generated at
Since the oscillating frequency of each switching element is increased, it is possible to suppress stress on circuit components due to a decrease in load impedance at low temperatures.

A ninth aspect of the present invention includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements that are alternately turned on and off at a high frequency. An inverter circuit that supplies high-frequency power to the load, and a voltage that includes a smoothing capacitor and is connected in parallel to the series circuit of the two switching elements and is applied to the series circuit of both switching elements only during a part of the output voltage of the rectifier circuit A drive transformer for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit, and an LC resonance circuit. A series circuit including a circuit and a load circuit including the load and a DC cut capacitor is connected, and the drive transformer is A primary winding connected between a connection point of the two switching elements and a load circuit, and two secondary windings turning on and off the two switching elements alternately. Characterized in that two impedance elements each connected to each of the switching elements and having a negative characteristic with respect to temperature are connected in series to each secondary winding. When the load impedance is low, the impedance of the impedance element connected in series to each secondary winding of the drive transformer is large, and the amplitude of the pulse voltage generated in each secondary winding of the drive transformer is low. Since the oscillation frequency of the switching element increases, the stress on circuit components due to the decrease in load impedance at low temperatures is suppressed. It is possible.

According to a tenth aspect of the present invention, in the eighth or ninth aspect, the impedance element is a series circuit of a resistor and a temperature-sensitive element having a negative temperature coefficient. The influence of the impedance element can be prevented.

According to an eleventh aspect of the present invention, in the first to tenth aspects, each of the switching elements is formed of a MOSFET.

According to a twelfth aspect of the present invention, in the first to eleventh aspects of the present invention, the inverter circuit includes one end of a DC output terminal of the rectifier circuit to which a DC cut capacitor is connected, and the two switching devices. A diode connected in the forward direction to the rectifier circuit is connected between one end of the series circuit of elements and the input current from the AC power supply can flow at high frequency even when the voltage of the AC power supply is near zero crossing. Since the impedance element having an impedance as small as possible is connected in parallel to the diode, by providing a parallel circuit of the impedance element and the diode, even if the voltage of the AC power supply is near the zero crossing, the power supply from the AC power supply is The input current can flow at high frequency, and a small filter that blocks high frequency components Harmonic component of the input current to the extent that provided between the rectifier circuit can be reduced.

According to a thirteenth aspect, in the twelfth aspect, the impedance element is a capacitor.

According to a fourteenth aspect of the present invention, in the first to thirteenth aspects, since the load is a discharge lamp, an appropriate voltage across the smoothing capacitor can be obtained regardless of the state of the discharge lamp. Necessary electric power can be supplied stably.

[0040]

(Embodiment 1) As shown in FIG. 1A, the circuit configuration of a power supply device according to the present embodiment is the same as the conventional configuration shown in FIG. The arrangement of circuit components on the rectangular printed circuit board 30 shown in FIG. The same components as those of the conventional configuration shown in FIG. However, the configuration of the load circuit 1 is not limited to the configuration of FIG.

The components of the circuit shown in FIG. 1A are mounted on the printed circuit board 30. The printed circuit board 30 has an AC power supply V at one end in the longitudinal direction (the left-right direction in FIG. 1B).
The power supply terminal 5 to which s is connected is provided, and the output terminals 6, 6 to which the discharge lamp La as a load is connected are provided on the other end side. That is, the printed board 30 has one end in the longitudinal direction on the input side and the other end on the output side.

The printed circuit board 30 has four diodes D1 to D4 constituting a rectifier circuit DB, a drive transformer CT and respective switching elements Q1 and Q2, a load circuit, from the input side at one end in the longitudinal direction to the output side at the other end. One leakage transformer T2 is arranged in this order. Here, the drive transformer CT is disposed on a straight line connecting the two switching elements Q1 and Q2 in the width direction of the printed circuit board 30 (the vertical direction in FIG. 1B). In short, drive transformer C
T is diodes D1 to D4 constituting the rectifier circuit DB,
Switching elements Q1, Q2, leakage transformer T2
It is located at a position surrounded by the surroundings. The other components are not shown.

Incidentally, the diodes D1 to D4, the switching elements Q1 and Q2, and the leakage transformer T2 constituting the rectifier circuit DB are elements which generate particularly large self-heating among the circuit components constituting the circuit shown in FIG. The drive transformer CT is arranged so as to receive all the radiant heat of these elements generating a large amount of heat.

However, in the power supply device of the present embodiment, even if the power is turned on at a low temperature and the impedance of the discharge lamp La is low, the diode D constituting the rectifier circuit DB can be used.
1 to D4, the switching elements Q1 and Q2, and the driving transformer C by the radiation heat of the leakage transformer T2.
Since T is heated and the saturation magnetic flux density of the drive transformer CT decreases, the turn-off of each switching element Q1 and Q2 is accelerated, and each switching element Q1 and Q
The operating frequency of the discharge lamp La shifts to the operating frequency of the steady operation, so that the stress on the circuit components due to the decrease in the impedance of the discharge lamp La at a low temperature can be suppressed. Therefore, in the power supply device of the present embodiment, it is not necessary to increase the rating of the element or to provide a special protection circuit.

In the present embodiment, as described above, the switching elements Q1 and Q2 are disposed so as to sandwich the drive transformer CT, and the respective secondary windings n21 and n22 of the drive transformer CT are connected to each other. Switching element Q
Since the wirings to the gates of the transistors 1 and Q2 can be made substantially equal and shorter, the inductance of the wirings can be reduced, and the generation of noise can be suppressed.

(Embodiment 2) The circuit configuration of a power supply device of this embodiment is the same as that of Embodiment 1, and is characterized by the arrangement of circuit components on a rectangular printed circuit board 30 shown in FIG. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, the driving transformer CT
Is arranged substantially at the center in the width direction of the printed circuit board 30, and both switching elements Q1 and Q2 are arranged at one end side in the width direction of the printed circuit board 30. In this embodiment, as in the first embodiment, the four diodes D1 to D4 constituting the rectifier circuit DB and the drive transformer CT extend from the input side at one end to the output side at the other end of the printed circuit board 30 in the longitudinal direction. And the switching elements Q1 and Q2, and the leakage transformer T2 of the load circuit 1, and the driving transformer CT constitutes the rectifier circuit DB.
1, Q2, disposed at a position surrounded by the leakage transformer T2. In short, the drive transformer CT is disposed at a position surrounded by the diodes D1 to D4, the switching elements Q1 and Q2, and the leakage transformer T2 that constitute the rectifier circuit DB.

In the power supply device of this embodiment, as in the first embodiment, even if the power is turned on at a low temperature and the impedance of the discharge lamp La is low, each of the diodes D1 to D4 constituting the rectifier circuit DB has Switching element Q1,
Q2, the drive transformer CT is heated by the radiation heat of the leakage transformer T2, and the saturation magnetic flux density of the drive transformer CT is reduced.
The turn-off of Q2 is accelerated, and the operating frequency of each of the switching elements Q1 and Q2 shifts to the operating frequency of the steady operation in a relatively short time.
, Stress on circuit components due to a decrease in the impedance of the circuit can be suppressed.

Also in the present embodiment, each of the secondary windings n21 and n22 of the driving transformer CT (see FIG. 1A).
Since the wiring from each to the gate of each of the switching elements Q1 and Q2 can be made substantially equal and short, the inductance of the wiring can be reduced and the generation of noise can be suppressed.

(Embodiment 3) As shown in FIG. 3A, the circuit configuration of the power supply device of the present embodiment is the same as the conventional configuration shown in FIG. This is characterized by the arrangement of circuit components on the printed circuit board 30. In addition,
The same components as those in the conventional configuration shown in FIG. However, the configuration of the load circuit 1 is not limited to the configuration of FIG.

The components of the circuit shown in FIG. 3A are mounted on the printed circuit board 30. The printed circuit board 30 has an AC power supply V at one end in the longitudinal direction (the left-right direction in FIG.
The power supply terminal 5 to which s is connected is provided, and the output terminals 6, 6 to which the discharge lamp La as a load is connected are provided on the other end side. That is, the printed board 30 has one end in the longitudinal direction on the input side and the other end on the output side.

The printed circuit board 30 has four diodes D1 to D4 constituting a rectifier circuit DB, a drive transformer CT and respective switching elements Q1 and Q2, a load circuit, from the input side at one end in the longitudinal direction to the output side at the other end. One leakage transformer T2 is arranged in this order. Here, the drive transformer CT is disposed on a straight line connecting the two switching elements Q1 and Q2 in the width direction of the printed circuit board 30 (vertical direction in FIG. 3B). In short, drive transformer C
T is diodes D1 to D4 constituting the rectifier circuit DB,
Switching elements Q1, Q2, leakage transformer T2
It is located at a position surrounded by the surroundings. The other components are not shown.

Incidentally, the diodes D1 to D4, the switching elements Q1 and Q2, and the leakage transformer T2 constituting the rectifier circuit DB are elements which generate particularly large self-heating among the circuit components constituting the circuit shown in FIG. The drive transformer CT is arranged so as to receive all the radiant heat of these elements generating a large amount of heat.

Thus, in the power supply device of the present embodiment, even if the power is turned on at a low temperature and the impedance of the discharge lamp La is low, the diode D constituting the rectifier circuit DB can be used.
1 to D4, the switching elements Q1 and Q2, and the driving transformer C by the radiation heat of the leakage transformer T2.
Since T is heated and the saturation magnetic flux density of the drive transformer CT decreases, the turn-off of each switching element Q1 and Q2 is accelerated, and each switching element Q1 and Q
The operating frequency of the discharge lamp La shifts to the operating frequency of the steady operation, so that the stress on the circuit components due to the decrease in the impedance of the discharge lamp La at a low temperature can be suppressed. Therefore, in the power supply device of the present embodiment, it is not necessary to increase the rating of the element or to provide a special protection circuit.

In the present embodiment, as described above, both switching elements Q1 and Q2 are disposed so as to sandwich the drive transformer CT, and the respective secondary windings n21 and n22 of the drive transformer CT are connected to the respective switching elements Q1 and Q2. Switching element Q
Since the wirings to the gates of the transistors 1 and Q2 can be made substantially equal and shorter, the inductance of the wirings can be reduced, and the generation of noise can be suppressed.

(Embodiment 4) The circuit configuration of the power supply device of this embodiment is the same as that of Embodiment 3, and is characterized by the arrangement of circuit components on a rectangular printed circuit board 30 shown in FIG. Note that the same components as those in the third embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, the driving transformer CT
Are arranged substantially at the center in the width direction of the printed circuit board 30, and the two switching elements Q1 and Q2 are arranged at one end side in the width direction of the printed circuit board 30. In the present embodiment, similarly to the third embodiment, four diodes D constituting the rectifier circuit DB extend from the input side at one end in the longitudinal direction of the printed circuit board 30 to the output side at the other end.
1 to D4, drive transformer CT and each switching element Q
1, Q2, and the leakage transformer T2 of the load circuit 1, and the drive transformer CT is disposed at a position surrounded by the diodes D1 to D4, the switching elements Q1, Q2, and the leakage transformer T2 that constitute the rectifier circuit DB. I have. In short, the drive transformer CT is composed of the diodes D1 to D4 forming the rectifier circuit DB and the switching element Q
1, Q2, disposed at a position surrounded by the leakage transformer T2.

Thus, in the power supply device of the present embodiment, the diodes D1 to D4 constituting the rectifier circuit DB, even if the power is turned on at a low temperature and the impedance of the discharge lamp La is low, similarly to the third embodiment. Switching element Q1,
Q2, the drive transformer CT is heated by the radiation heat of the leakage transformer T2, and the saturation magnetic flux density of the drive transformer CT is reduced.
The turn-off of Q2 is accelerated, and the operating frequency of each of the switching elements Q1 and Q2 shifts to the operating frequency of the steady operation in a relatively short time.
, Stress on circuit components due to a decrease in the impedance of the circuit can be suppressed.

Also in the present embodiment, the wiring from each of the secondary windings n21 and n22 of the drive transformer CT to the gate of each of the switching elements Q1 and Q2 can be made substantially equal and short, so that the wiring inductance is reduced. And the occurrence of noise can be suppressed.

(Embodiment 5) The power supply device of the present embodiment
This is substantially the same as the conventional configuration shown in FIG. 14, and is different from the conventional configuration shown in FIG. There are features. Note that the same components as those of the conventional configuration shown in FIG. 14 are denoted by the same reference numerals.

Also in this embodiment, as in the above-described conventional configuration, the AC power supply Vs is input to the rectifier circuit DB via the high-frequency blocking filter circuit F and is subjected to full-wave rectification. The rectifier circuit DB includes four diodes D1 to D4.
And a diode bridge composed of The filter circuit F is provided to prevent a high-frequency current from leaking from the inverter circuit INV to the AC power supply Vs.

The capacitor C2 is connected between the DC output terminals of the rectifier circuit DB, and the inverter circuit INV is connected.

In the inverter circuit INV, a series circuit of a pair of switching elements Q1 and Q2 composed of MOSFETs is connected between the DC output terminals of the rectifier circuit DB via a series circuit of diodes D5 and D6. A smoothing capacitor C0 is connected in parallel to a series circuit of the two switching elements Q1 and Q2, and a resonance capacitor C4 as an impedance element is connected in parallel to the diode D6. Connection points of diodes D5 and D6 and switching elements Q1 and Q
2 is connected to a DC cut capacitor C3.
And a series circuit of the load circuit 1 and the drive transformer CT.

The load circuit 1 includes a leakage transformer T2 having a primary winding connected between a DC cut capacitor C3 and a driving transformer CT, and a load La connected between secondary windings of the leakage transformer T2. And a resonance capacitor C5 connected in parallel to the load La. Here, a discharge lamp is used as the load La, and the filament of the discharge lamp La is not shown in FIG. ing. The capacitor C5 forms an LC resonance circuit together with the leakage inductance of the leakage transformer T2.

The drive transformer CT has the primary winding n1 of the drive transformer CT connected between the connection point of the switching elements Q1 and Q2 and the primary winding of the leakage transformer T2, and is provided on the drive transformer CT. Two secondary windings n2
1, n22, a series circuit of a secondary winding n21 and a gate resistor R1 is connected between the gate and source of the switching element Q1, and a series circuit of the other secondary winding n22 and a gate resistor R2 is connected to a switching element. It is connected between the gate and source of Q2. Therefore, the drive transformer CT becomes a means for self-exciting the switching elements Q1 and Q2, and the switching elements Q1 and Q2 are turned on and off alternately at a high frequency. The above-described impedance element Z is connected in parallel to the primary winding n1 of the drive transformer CT. The impedance element Z has a resistance R13 and a temperature-sensitive coefficient having a positive temperature coefficient (PCT) as shown in FIG. It is constituted by a series circuit with an element (for example, a positive temperature coefficient resistor, a positive temperature coefficient thermistor) R0.

The operation of the circuit shown in FIG. 5 will be briefly described below.

Now, assuming that a steady operation is performed, the switching element Q1 and the switching element Q2 are alternately turned on and off. In the latter half of the period when the switching element Q2 is on, the smoothing capacitor C0 is used as a power source with the smoothing capacitor C0 as a power supply. -Capacitor C4-Capacitor C3-
A resonance current flows through the load circuit 1 through the load circuit 1-the primary winding n of the driving transformer CT 1-the switching element Q2-the smoothing capacitor C0, and the voltage obtained by adding the voltage across the capacitor C4 to the output voltage of the rectifier circuit DB. Smoothing capacitor C
0, the AC power supply Vs-rectifier circuit D
B-diode D5-capacitor C3-load circuit 1-primary winding n of drive transformer CT1-switching element Q2
-A rectifier circuit DB-a resonance current flows through the load circuit 1 through the path of the AC power supply Vs (at this time, the input current is drawn from the AC power supply Vs, and the current value of the input current is a value proportional to the instantaneous value of the AC power supply Vs) Becomes).

Next, when the switching element Q2 is turned off, the regenerative current from the leakage transformer T2 of the load circuit 1 is applied to the leakage transformer T2-the driving transformer CT.
Next winding n1-parasitic diode of switching element Q1-
The current flows through the path of the smoothing capacitor C0, the rectifier circuit DB, the AC power supply Vs, the rectifier circuit DB, the diode D5, the capacitor C3, and the leakage transformer T2.
s, the input current is drawn, and the current value of the input current becomes a value proportional to the instantaneous value of the AC power supply Vs).

Thereafter, when the regenerative current of the leakage transformer T2 becomes zero, the capacitors C3 to C3
-A capacitor C4-a switching element Q1-a primary winding n of the driving transformer CT-a load circuit 1-a resonance current flows through the load circuit 1 through the path of the capacitor C3, and a charge stored in the capacitor C4 when the switching element Q2 is turned on. When the charge of the capacitor C4 becomes zero, the resonance current flows from the capacitor C3 to the load circuit 1 through the path of the capacitor C3, the diode D6, the switching element Q1, the primary winding n of the drive transformer CT, the load circuit 1 and the capacitor C3. Flows.

Next, when the switching element Q2 is turned on, the regenerative current of the leakage transformer T2 of the load circuit 1 is changed to the leakage transformer T2-capacitor C3-diode D6-smoothing capacitor C0-switching element Q2
Of the primary winding n1- of the driving diode CT
It flows on the path of the leakage transformer T2. Thus, when the electromagnetic energy of the leakage transformer T2 is released,
Again, the resonance current flows through the load circuit 1 using the smoothing capacitor C0 as a power supply, and the above operation is repeated.

By repeating these series of operations, high-frequency power is supplied to the discharge lamp La. By the way, in the circuit configuration shown in FIG. 5, since the filter circuit F for blocking high frequency is provided, the current input through the filter circuit F has a sinusoidal waveform substantially proportional to the voltage of the AC power supply Vs, A current distortion is small and a relatively high input power factor can be obtained. Further, since the regenerative current of the leakage transformer T2 is used for charging the smoothing capacitor C0, a stable power supply for the inverter circuit INV can be secured.

The above operation is basically the same as the operation of the conventional configuration shown in FIG. 14, but in this embodiment,
Since the impedance element Z is connected in parallel to the primary winding n1 of the drive transformer CT, when the power is turned on at a low temperature and the impedance of the discharge lamp La as a load is low, the primary winding of the drive transformer CT is formed. The ratio of the current flowing in the impedance element Z to the current flowing in n1 increases, and as a result, the amplitude of the pulse voltage generated in each of the secondary windings n21 and n22 of the drive transformer CT decreases, and the switching elements Q1, Since the operating frequency of Q2 increases, the smoothing capacitor C0 can be prevented from being charged more than necessary, and the discharge lamp La at low temperature can be prevented.
Of the circuit components (smoothing capacitor C0, switching elements Q1 and Q2, etc.) due to the decrease in the impedance of.

The above operation is summarized as shown in FIG. Here, FIG. 7A shows the current flowing through the switching element Q2 in the above-described conventional configuration, and FIG. 7B shows the current flowing through the gate of the switching element Q2 at a low temperature in the above-described conventional configuration.
Gate voltage (drive signal) applied between sources, (b)
In the present embodiment, the switching element Q
The gate voltage (drive signal) applied between the gate and the source of the switching element Q2 in the above-described conventional configuration at a low temperature (the voltage across the switching element Q2), and (d) in this embodiment. 6 shows ON / OFF of the switching element Q2 (voltage across the switching element Q2) at a low temperature.

The switching element Q2 is shown in FIG.
As shown in FIG. 7D, the transistor turns on when the gate voltage shown in FIG. 7B becomes equal to or higher than the threshold voltage Vth of the switching element Q2, and thereafter turns off when the gate voltage becomes lower than the threshold voltage Vth. In the present embodiment, each secondary winding n2 of the drive transformer CT is at a lower temperature than the above-described conventional configuration.
1 and n22, the amplitude of the pulse voltage is reduced, and the amplitude of the gate voltage of the switching element Q2 is lower than that in FIG. 7B, as shown in FIG. The period until Q2 is turned off is shortened, and the switching element Q2 is turned on and off as shown in FIG. 7 (d). Get higher. Although only the switching element Q2 has been described above, the same applies to the switching element Q1.

When the temperatures of the discharge lamp La and the drive transformer CT rise, the impedance of the discharge lamp La approaches the impedance at the time of steady lighting, so that the discharge lamp La operates in the output state at the time of steady lighting.

By the way, the capacitor C4 in the inverter circuit INV is set to have an impedance small enough to allow the input current from the AC power supply Vs to flow at a high frequency even when the voltage of the AC power supply Vs is near zero cross. Since the parallel circuit of the capacitor C4 and the diode D6 is provided, even if the voltage of the AC power supply Vs is near the zero cross, the AC power supply Vs
Can flow the input current from the power supply at a high frequency, and the harmonic component of the input current can be reduced only by providing a small filter circuit F between the AC power supply Vs and the rectifier circuit DB.

In the present embodiment, the impedance element Z connected in parallel to the primary winding n1 of the drive transformer CT is formed by the series circuit of the resistor R13 and the temperature sensing element R0 having a positive temperature coefficient as described above. With the configuration, it is possible to prevent the impedance element Z from affecting the resonance frequency of the LC resonance circuit.

(Embodiment 6) The power supply of this embodiment is
It is substantially the same as the conventional configuration shown in FIG. 15, and is characterized in that, as shown in FIG. There is. Note that the same components as those of the conventional configuration shown in FIG. 15 are denoted by the same reference numerals.

Also in the present embodiment, as in the above-described conventional configuration, the AC power supply Vs is input to the rectifier circuit DB via the high-frequency blocking filter circuit F to be full-wave rectified. The rectifier circuit DB includes four diodes D1 to D4.
And a diode bridge composed of The filter circuit F is provided to prevent a high-frequency current from leaking from the inverter circuit INV to the AC power supply Vs.
A series circuit of a smoothing capacitor C0 and a diode D8 is connected in parallel to a series circuit of both switching elements Q1 and Q2, and a capacitor C6 is connected in parallel. Here, the diode D8 has an anode connected to the DC output terminal on the negative side of the rectifier circuit DB, and a smoothing capacitor C0.
To form a discharge path for the smoothing capacitor C0. Further, a diode D7 is connected between a connection point between the smoothing capacitor C0 and the diode D8 and a connection point between the capacitor C3 and the leakage transformer T2. The diode D7 has an anode connected to the diode D7.
8 and the cathode is connected to a connection point between the capacitor C3 and the leakage transformer T2.
The partial smoothing circuit 2 is constituted by the smoothing capacitor C0, the diodes D7 and D8, and the capacitor C6.

The drive transformer CT has the primary winding n1 of the drive transformer CT connected between the connection point of the switching elements Q1 and Q2 and the primary winding of the leakage transformer T2, and is provided on the drive transformer CT. Two secondary windings n2
1, n22, a series circuit of a secondary winding n21 and a gate resistor R1 is connected between the gate and source of the switching element Q1, and a series circuit of the other secondary winding n22 and a gate resistor R2 is connected to a switching element. It is connected between the gate and source of Q2. Therefore, the drive transformer CT becomes a means for self-exciting the switching elements Q1 and Q2, and the switching elements Q1 and Q2 are turned on and off alternately at a high frequency.

The power supply device of this embodiment has a drive transformer C
The above-described impedance element Z is connected in parallel to the primary winding n1 of T. The impedance element Z has a resistance R13 and a temperature-sensitive element having a positive temperature coefficient (PCT) as shown in FIG. And a temperature coefficient resistor, a positive temperature coefficient thermistor) R0.

The operation of the circuit shown in FIG. 8 will be briefly described below.

Now, assuming that a steady operation is performed, the switching element Q1 and the switching element Q2 are alternately turned on and off.
A resonance current flows through the load circuit 1 through a path of the capacitor C3-the load circuit 1-the primary winding n of the drive transformer CT 1-the switching element Q2-the partial smoothing circuit 2, and the voltage across the capacitor C4 is output to the rectifier circuit DB. When the added voltage balances the voltage between both ends of the partial smoothing circuit 2, the AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-load circuit 1-primary winding n of drive transformer CT1-switching element Q2-rectifier circuit DB A resonance current flows through the load circuit 1 through the path of the AC power supply Vs (in this case, the input current is drawn from the AC power supply Vs, and the current value of the input current is
s) is proportional to the instantaneous value of s).

Next, when the switching element Q2 is turned off, the regenerative current from the leakage transformer T2 of the load circuit 1 is applied to the leakage transformer T2-the driving transformer CT.
Next winding n1-parasitic diode of switching element Q1-
The current flows through the path of the partial smoothing circuit 2-rectifier circuit DB-AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-leakage transformer T2. (Also at this time, the input current is drawn from the AC power supply Vs. The value is proportional to the instantaneous value of the AC power supply Vs).

Thereafter, when the regenerative current of the leakage transformer T2 becomes zero, the capacitors C3 to C3
-A capacitor C4-a switching element Q1-a primary winding n of the driving transformer CT-a load circuit 1-a resonance current flows through the load circuit 1 through the path of the capacitor C3, and a charge stored in the capacitor C4 when the switching element Q2 is turned on. When the charge of the capacitor C4 becomes zero, the resonance current flows from the capacitor C3 to the load circuit 1 through the path of the capacitor C3, the diode D6, the switching element Q1, the primary winding n of the drive transformer CT, the load circuit 1 and the capacitor C3. Flows.

Next, when the switching element Q2 is turned on, the regenerative current of the leakage transformer T2 of the load circuit 1 is changed to a leakage transformer T2-capacitor C3-diode D6-partial smoothing circuit 2-parasitic diode of the switching element Q2-drive transformer CT A regenerative current flows through the path of the primary winding n1-leakage transformer T2.

By repeating these series of operations, high-frequency power is supplied to the discharge lamp La. by the way,
In the circuit configuration shown in FIG. 8 as well, since a filter circuit F for blocking high frequency is provided, the current input through the filter circuit F has a sinusoidal waveform substantially proportional to the voltage of the AC power supply Vs. A relatively low input power factor with little distortion can be obtained. Further, since the regenerative current of the leakage transformer T2 is used for charging the smoothing capacitor C0 of the partial smoothing circuit 2, a stable power supply for the inverter circuit INV can be secured.

On the other hand, in the partial smoothing circuit 2, when the switching element Q2 is turned on, the AC power supply Vs-rectifier circuit DB-
Smoothing capacitor C0-Diode D7-Leakage transformer T2-Primary winding n of drive transformer CT1-Switching element Q2-Rectifier circuit DB-Charged through a path passing through AC power supply Vs, and is higher than the peak value of the output voltage of rectifier circuit DB. Smoothed at low voltage. When the peak value of the power supply voltage is lower than the voltage of the smoothing capacitor C0, power is supplied from the smoothing capacitor C0 to the inverter circuit INV.

The above operation is basically the same as the operation of the conventional configuration shown in FIG. 15, but in this embodiment,
Since the impedance element Z is connected in parallel to the primary winding n1 of the drive transformer CT, when the power is turned on at a low temperature and the impedance of the discharge lamp La, which is the load, is low, the drive transformer is similar to the fifth embodiment. The ratio of the current flowing in the impedance element Z to the current flowing in the primary winding n1 of the CT increases, and as a result, the amplitude of the pulse voltage generated in each of the secondary windings n21 and n22 of the drive transformer CT decreases. , Each switching element Q
1, the operating frequency of Q2 is increased, so that the smoothing capacitor C0 can be prevented from being charged more than necessary, and the circuit components (smoothing capacitor C0, switching element Q
1, Q2). That is, also in the present embodiment, the secondary windings n21 and n22 of the drive transformer CT are at a lower temperature than in the above-described conventional configuration.
The amplitude of the pulse voltage generated in each case decreases, and FIG.
7B, the amplitude of the gate voltage of the switching element Q2 is lower than that in FIG. 7B, so that the period until the switching element Q2 is turned off is shortened. The switching element Q2 is turned on and off as shown in FIG. 7D, and the operating frequency of the switching element Q2 is higher than in the case where it is turned on and off as shown in FIG. 7C.

When the temperatures of the discharge lamp La and the drive transformer CT rise, the impedance of the discharge lamp La approaches the impedance at the time of steady lighting, so that the discharge lamp La operates in the output state at the time of steady lighting.

(Embodiment 7) The basic configuration of a power supply device of this embodiment is substantially the same as that of Embodiment 6, and as shown in FIG. An inductor L2 is inserted, a connection point between the inductor L2 and the diode D8, a primary winding n1 of the leakage transformer T2 and a primary winding n1 of the drive transformer CT.
A difference is that a diode D7 is connected between the connection point and the connection point. That is, in the present embodiment, the smoothing capacitor C0, the inductor L2, the diodes D7, D8,
The partial smoothing circuit 2 is constituted by the capacitor C6.
Note that the same components as those in the sixth embodiment are denoted by the same reference numerals, and description thereof is omitted.

Hereinafter, the operation of the power supply device according to the present embodiment will be briefly described.

Now, assuming that a steady operation is performed, the switching element Q1 and the switching element Q2 are alternately turned on and off. In the latter half of the period when the switching element Q2 is on, the partial smoothing circuit 2-capacitor C4-
A resonance current flows through the load circuit 1 through a path of the capacitor C3, the load circuit 1, the primary winding n of the drive transformer CT, the switching element Q2, and the partial smoothing circuit 2. When the added voltage balances the voltage between both ends of the partial smoothing circuit 2, a path of the AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-load circuit 1-drive transformer CT-switching element Q2-rectifier circuit DB-AC power supply Vs (In this case, the input current is drawn from the AC power supply Vs, and the current value of the input current becomes a value proportional to the instantaneous value of the AC power supply Vs).

Next, when the switching element Q2 is turned off, the regenerative current from the leakage transformer T2 of the load circuit 1 is applied to the leakage transformer T2-the drive transformer CT.
Next winding n1-parasitic diode of switching element Q1-
The current flows through the path of the partial smoothing circuit 2-rectifier circuit DB-AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-leakage transformer T2. (Also at this time, the input current is drawn from the AC power supply Vs. The value is proportional to the instantaneous value of the AC power supply Vs).

Thereafter, when the regenerative current of the leakage transformer T2 becomes zero, the capacitors C3 to C3
A resonance current flows through the load circuit 1 through the path of the capacitor C4, the switching element Q1, the driving transformer CT, the load circuit 1, and the capacitor C3, and when the switching element Q2 is turned on, the electric charge stored in the capacitor C4 is released and the capacitor C4 is discharged. When the charge becomes zero, a resonance current flows from the capacitor C3 to the load circuit 1 through the path of the capacitor C3, the diode D6, the switching element Q1, the primary winding n of the drive transformer CT, the load circuit 1, and the capacitor C3.

Next, when the switching element Q2 is turned on, the regenerative current of the leakage transformer T2 of the load circuit 1 is changed to the leakage transformer T2-capacitor C3-diode D6-partial smoothing circuit 2-parasitic diode of the switching element Q2-drive transformer CT A regenerative current flows through the path of the primary winding n1-leakage transformer T2.

By repeating these series of operations, high-frequency power is supplied to the discharge lamp La. by the way,
Also in the circuit configuration shown in FIG. 9, since the filter circuit F for blocking high frequency is provided, the current input through the filter circuit F has a sinusoidal waveform substantially proportional to the voltage of the AC power supply Vs. It is possible to obtain a relatively high input power factor with little distortion.

On the other hand, in the partial smoothing circuit 2, when the switching element Q2 is turned on, the AC power supply Vs-rectifier circuit DB-
Smoothing capacitor C0-Inductor L2-Diode D7
-The primary winding n of the driving transformer CT-the switching element Q2-the rectifier circuit DB-is charged through a path passing through the AC power supply Vs, and is smoothed at a voltage lower than the peak value of the output voltage of the rectifier circuit DB. When the peak value of the power supply voltage is lower than the voltage of the smoothing capacitor C0, power is supplied from the smoothing capacitor C0 to the inverter circuit INV.

The above operation is basically the same as the operation of the conventional configuration shown in FIG. 15, but in this embodiment,
Since the impedance element Z is connected in parallel to the primary winding n1 of the drive transformer CT, when the power is turned on at a low temperature and the impedance of the discharge lamp La, which is the load, is low, the drive transformer is similar to the fifth embodiment. The ratio of the current flowing in the impedance element Z to the current flowing in the primary winding n1 of the CT increases, and as a result, the amplitude of the pulse voltage generated in each of the secondary windings n21 and n22 of the drive transformer CT decreases. , Each switching element Q
1, the operating frequency of Q2 is increased, so that the smoothing capacitor C0 can be prevented from being charged more than necessary, and the circuit components (smoothing capacitor C0, switching element Q
1, Q2). That is, also in the present embodiment, the secondary windings n21 and n22 of the drive transformer CT are at a lower temperature than in the above-described conventional configuration.
The amplitude of the pulse voltage generated in each case decreases, and FIG.
7B, the amplitude of the gate voltage of the switching element Q2 is lower than that in FIG. 7B, so that the period until the switching element Q2 is turned off is shortened. The switching element Q2 is turned on and off as shown in FIG. 7D, and the operating frequency of the switching element Q2 is higher than in the case where it is turned on and off as shown in FIG. 7C.

When the temperatures of the discharge lamp La and the drive transformer CT rise, the impedance of the discharge lamp La approaches the impedance at the time of steady lighting, so that the discharge lamp La operates in the output state at the time of steady lighting.

(Embodiment 8) The power supply of this embodiment is
It is substantially the same as the conventional configuration shown in FIG. 14, and as shown in FIG. 10, two impedance elements Z1 and Z2 having negative characteristics with respect to temperature are respectively connected to the secondary windings n21 and n22 of the drive transformer CT. The feature is that it is connected in series. Further, resistors R3 and R4 are connected between the gate and source of each of the switching elements Q1 and Q2, respectively. Note that the same components as those of the conventional configuration shown in FIG. 14 are denoted by the same reference numerals.

Also in this embodiment, the AC power supply Vs is full-wave rectified by being input to the rectifier circuit DB via the high frequency blocking filter circuit F, similarly to the conventional configuration described above. The rectifier circuit DB includes four diodes D1 to D4.
And a diode bridge composed of The filter circuit F is provided to prevent a high-frequency current from leaking from the inverter circuit INV to the AC power supply Vs.

The capacitor C2 is connected between the DC output terminals of the rectifier circuit DB, and the inverter circuit INV is connected.

In the inverter circuit INV, a series circuit of a pair of switching elements Q1 and Q2 composed of MOSFETs is connected between the DC output terminals of the rectifier circuit DB via a series circuit of diodes D5 and D6. A smoothing capacitor C0 is connected in parallel to a series circuit of the two switching elements Q1 and Q2, and a resonance capacitor C4 as an impedance element is connected in parallel to the diode D6. Connection points of diodes D5 and D6 and switching elements Q1 and Q
2 is connected to a DC cut capacitor C3.
And a series circuit of the load circuit 1 and the drive transformer CT.

The load circuit 1 includes a leakage transformer T2 having a primary winding connected between a DC cut capacitor C3 and a driving transformer CT, and a load La connected between secondary windings of the leakage transformer T2. And a resonance capacitor C5 connected in parallel to the load La. Here, a discharge lamp is used as the load La. Although the filament of the discharge lamp La is not shown in FIG. 10, the capacitor C5 is connected between the non-power-supply-side ends of both filaments of the discharge lamp La. ing. The capacitor C5 forms an LC resonance circuit together with the leakage inductance of the leakage transformer T2.

The drive transformer CT has the primary winding n1 of the drive transformer CT connected between the connection point of the switching elements Q1 and Q2 and the primary winding of the leakage transformer T2, and is provided on the drive transformer CT. Two secondary windings n2
1, n22, a series circuit of a secondary winding n21 and a gate resistor R1 is connected between the gate and source of the switching element Q1, and a series circuit of the other secondary winding n22 and a gate resistor R2 is connected to a switching element. It is connected between the gate and source of Q2. Therefore, the drive transformer CT becomes a means for self-exciting the switching elements Q1 and Q2, and the switching elements Q1 and Q2 are turned on and off alternately at a high frequency. Further, each secondary winding n21, n2 of the drive transformer CT
2, the impedance elements Z1 and Z2 are connected in series.
Represents the resistance R13 and the negative temperature coefficient (NC) as shown in FIG.
T) and a temperature sensitive element (eg, a negative temperature coefficient resistor, a negative temperature coefficient thermistor) R0 ′.

The operation of the circuit shown in FIG. 10 will be briefly described below.

Assuming that a steady operation is performed, the switching element Q1 and the switching element Q2 are alternately turned on and off. In the latter half of the period when the switching element Q2 is on, the smoothing capacitor C0 is used as a power source by using the smoothing capacitor C0 as a power supply. -Capacitor C4-Capacitor C3-
A resonance current flows through the load circuit 1 through the load circuit 1-the primary winding n of the driving transformer CT 1-the switching element Q2-the smoothing capacitor C0, and the voltage obtained by adding the voltage across the capacitor C4 to the output voltage of the rectifier circuit DB. Smoothing capacitor C
0, the AC power supply Vs-rectifier circuit D
B-diode D5-capacitor C3-load circuit 1-primary winding n of drive transformer CT1-switching element Q2
-A rectifier circuit DB-a resonance current flows through the load circuit 1 through the path of the AC power supply Vs (at this time, the input current is drawn from the AC power supply Vs, and the current value of the input current is a value proportional to the instantaneous value of the AC power supply Vs) Becomes).

Next, when the switching element Q2 is turned off, the regenerative current from the leakage transformer T2 of the load circuit 1 is applied to the leakage transformer T2-the driving transformer CT.
Next winding n1-parasitic diode of switching element Q1-
The current flows through the path of the smoothing capacitor C0, the rectifier circuit DB, the AC power supply Vs, the rectifier circuit DB, the diode D5, the capacitor C3, and the leakage transformer T2.
s, the input current is drawn, and the current value of the input current becomes a value proportional to the instantaneous value of the AC power supply Vs).

Thereafter, when the regenerative current of the leakage transformer T2 becomes zero, the capacitors C3 to C3
-A capacitor C4-a switching element Q1-a primary winding n of the driving transformer CT-a load circuit 1-a resonance current flows through the load circuit 1 through the path of the capacitor C3, and a charge stored in the capacitor C4 when the switching element Q2 is turned on. When the charge of the capacitor C4 becomes zero, the resonance current flows from the capacitor C3 to the load circuit 1 through the path of the capacitor C3, the diode D6, the switching element Q1, the primary winding n of the drive transformer CT, the load circuit 1 and the capacitor C3. Flows.

Next, when the switching element Q2 is turned on, the regenerative current of the leakage transformer T2 of the load circuit 1 is changed to the leakage transformer T2-capacitor C3-diode D6-smoothing capacitor C0-switching element Q2
Of the primary winding n1- of the driving diode CT
It flows on the path of the leakage transformer T2. Thus, when the electromagnetic energy of the leakage transformer T2 is released,
Again, the resonance current flows through the load circuit 1 using the smoothing capacitor C0 as a power supply, and the above operation is repeated.

By repeating a series of these operations, high-frequency power is supplied to the discharge lamp La. By the way, in the circuit configuration shown in FIG. 10, since the filter circuit F for blocking high frequency is provided, the current input through the filter circuit F has a sinusoidal waveform substantially proportional to the voltage of the AC power supply Vs, The current distortion is small, and a relatively high input power factor can be obtained. Further, since the regenerative current of the leakage transformer T2 is used for charging the smoothing capacitor C0, a stable power supply for the inverter circuit INV can be secured.

The above operation is basically the same as the operation of the conventional configuration shown in FIG. 14, but in this embodiment,
Since the impedance elements Z1 and Z2 are connected in series to the respective secondary windings n21 and n22 of the drive transformer CT, when the power is turned on at a low temperature and the impedance of the discharge lamp La as a load is low, the impedance is reduced. Since the impedance of each of the elements Z1 and Z2 increases, the voltage across the resistors R3 and R4 (the voltage across the resistor R3 is a voltage determined by the voltage division of the impedance element Z1, the resistors R1 and R3, and the voltage across the resistor R4. Decreases the voltage determined by the voltage division of the impedance element Z2, the resistor R2, and the resistor R3). As a result, the amplitude of the gate voltage (drive signal) of the switching elements Q1, Q2 decreases, and the switching elements Q1, Q2 Since the operating frequency increases, it is possible to prevent the smoothing capacitor C0 from being charged more than necessary. , It is possible to suppress the stress on the circuit components due to a decrease in the impedance of the discharge lamp La at a low temperature (smoothing capacitor C0, a switching element Q1, Q2).

When the temperatures of the discharge lamp La and the drive transformer CT rise, the impedance of the discharge lamp La approaches the impedance at the time of steady lighting, so that the discharge lamp La operates in the output state at the time of steady lighting.

In the present embodiment, the impedance elements Z1 and Z2 connected in series to the respective secondary windings n21 and n22 of the drive transformer CT are replaced by the temperature sensitive element having the resistance R13 and the negative temperature coefficient as described above. R0 ', the impedance element Z
1, Z2 can be prevented from affecting the resonance frequency of the LC resonance circuit.

(Embodiment 9) The power supply of this embodiment is
This is substantially the same as the conventional configuration shown in FIG. 15, and as shown in FIG. 12, each of two impedance elements Z1 and Z2 having a negative characteristic with respect to temperature is connected to each of the secondary windings n21 and n22 of the drive transformer CT. The feature is that it is connected in series. Further, resistors R3 and R4 are connected between the gate and source of each of the switching elements Q1 and Q2, respectively. Note that the same components as those of the conventional configuration shown in FIG. 15 are denoted by the same reference numerals.

Also in this embodiment, as in the above-described conventional configuration, the AC power supply Vs is input to the rectifier circuit DB via the high-frequency blocking filter circuit F to be full-wave rectified. The rectifier circuit DB includes four diodes D1 to D4.
And a diode bridge composed of The filter circuit F is provided to prevent a high-frequency current from leaking from the inverter circuit INV to the AC power supply Vs.
A series circuit of a smoothing capacitor C0 and a diode D8 is connected in parallel to a series circuit of both switching elements Q1 and Q2, and a capacitor C6 is connected in parallel. Here, the diode D8 has an anode connected to the DC output terminal on the negative side of the rectifier circuit DB, and a smoothing capacitor C0.
To form a discharge path for the smoothing capacitor C0. Further, a diode D7 is connected between a connection point between the smoothing capacitor C0 and the diode D8 and a connection point between the capacitor C3 and the leakage transformer T2. The diode D7 has an anode connected to the diode D7.
8 and the cathode is connected to a connection point between the capacitor C3 and the leakage transformer T2.
The partial smoothing circuit 2 is constituted by the smoothing capacitor C0, the diodes D7 and D8, and the capacitor C6.

The drive transformer CT has the primary winding n1 of the drive transformer CT connected between the connection point of the switching elements Q1 and Q2 and the primary winding of the leakage transformer T2, and is provided on the drive transformer CT. Two secondary windings n2
1, n22, a series circuit of a secondary winding n21 and a gate resistor R1 is connected between the gate and source of the switching element Q1, and a series circuit of the other secondary winding n22 and a gate resistor R2 is connected to a switching element. It is connected between the gate and source of Q2. Therefore, the drive transformer CT becomes a means for self-exciting the switching elements Q1 and Q2, and the switching elements Q1 and Q2 are turned on and off alternately at a high frequency. Further, each secondary winding n21, n2 of the drive transformer CT
2, the impedance elements Z1 and Z2 are connected in series.
Is constituted by a series circuit of a resistor R13 and a temperature sensitive element (for example, a negative temperature coefficient resistor, a negative temperature coefficient thermistor) R0 'having a negative temperature coefficient (NCT) as shown in FIG.

The operation of the circuit shown in FIG. 12 will be briefly described below.

Assuming that a steady operation is performed, the switching element Q1 and the switching element Q2 are alternately turned on and off. In the latter half of the period when the switching element Q2 is on, the partial smoothing circuit 2-capacitor C4-
A capacitor C3-load circuit 1-driving transformer CT-switching element Q2-partial smoothing circuit 2
When the voltage obtained by adding the voltage across the capacitor C4 to the output voltage of the rectifier circuit DB is balanced with the voltage across the partial smoothing circuit 2, the AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-load circuit 1—the primary winding n of the driving transformer CT 1—the switching element Q2—the rectifier circuit DB—the resonant current flows through the load circuit 1 through the path of the AC power supply Vs (at this time, the input current is drawn from the AC power supply Vs and the input The current value of the current is a value proportional to the instantaneous value of the AC power supply Vs).

Next, when the switching element Q2 is turned off, the regenerative current from the leakage transformer T2 of the load circuit 1 is applied to the leakage transformer T2-the driving transformer CT.
Next winding n1-parasitic diode of switching element Q1-
The current flows through the path of the partial smoothing circuit 2-rectifier circuit DB-AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-leakage transformer T2. (Also at this time, the input current is drawn from the AC power supply Vs. The value is proportional to the instantaneous value of the AC power supply Vs).

Thereafter, when the regenerative current of the leakage transformer T2 becomes zero, the capacitors C3 to C3
-A capacitor C4-a switching element Q1-a primary winding n of the driving transformer CT-a load circuit 1-a resonance current flows through the load circuit 1 through the path of the capacitor C3, and a charge stored in the capacitor C4 when the switching element Q2 is turned on. When the charge of the capacitor C4 becomes zero, a resonance current flows from the capacitor C3 to the capacitor C3, the diode D6, the switching element Q1, the primary winding n of the driving transformer CT, the load circuit 1, and the capacitor C3.

Next, when the switching element Q2 is turned on, the regenerative current of the leakage transformer T2 of the load circuit 1 is changed to the leakage transformer T2-capacitor C3-diode D6-partial smoothing circuit 2-parasitic diode of switching element Q2-drive transformer CT A regenerative current flows through the path of the primary winding n1-leakage transformer T2.

By repeating these series of operations, high-frequency power is supplied to the discharge lamp La. by the way,
Also in the circuit configuration shown in FIG. 12, since the filter circuit F for blocking high frequency is provided, the current input through the filter circuit F has a sinusoidal waveform substantially proportional to the voltage of the AC power supply Vs, and the harmonic current A relatively low input power factor with little distortion can be obtained. Further, since the regenerative current of the leakage transformer T2 is used for charging the smoothing capacitor C0 of the partial smoothing circuit 2, a stable power supply for the inverter circuit INV can be secured.

On the other hand, in the partial smoothing circuit 2, when the switching element Q2 is turned on, the AC power supply Vs-rectifier circuit DB-
Smoothing capacitor C0-Diode D7-Leakage transformer T2-Primary winding n of drive transformer CT1-Switching element Q2-Rectifier circuit DB-Charged through a path passing through AC power supply Vs, and is higher than the peak value of the output voltage of rectifier circuit DB. Smoothed at low voltage. When the peak value of the power supply voltage is lower than the voltage of the smoothing capacitor C0, power is supplied from the smoothing capacitor C0 to the inverter circuit INV.

The above operation is basically the same as the operation of the conventional configuration shown in FIG. 15, but in this embodiment,
As in the eighth embodiment, each secondary winding n2 of the driving transformer CT
1 and n22, respectively.
2 are connected in series, and when the power is turned on at a low temperature and the impedance of the discharge lamp La as a load is low, the impedance of each of the impedance elements Z1 and Z2 becomes high. (The voltage across the resistor R3 is a voltage determined by the voltage division of the impedance element Z1, the resistor R1, and the resistor R3, and the voltage across the resistor R4 is the voltage across the impedance element Z2 and the resistor R2.
The voltage determined by the voltage division of the switching element Q1 and the resistor R3) decreases, and as a result, the amplitude of the gate voltage (drive signal) of the switching elements Q1 and Q2 decreases, and the switching elements Q1 and Q2
Of the discharge lamp La can be prevented from being charged more than necessary, and the circuit components (smoothing capacitor C0, switching elements Q1, Q2
Etc.) can be reduced.

When the temperatures of the discharge lamp La and the drive transformer CT rise, the impedance of the discharge lamp La approaches the impedance at the time of steady lighting, so that the operation is performed in the output state at the time of steady lighting.

(Embodiment 10) The basic configuration of a power supply device according to this embodiment is substantially the same as that of Embodiment 9, and as shown in FIG. 13, a portion between the smoothing capacitor C0 and the diode D8 in the partial smoothing circuit 2. A point where the inductor L2 is inserted and a diode D7 is connected between a connection point between the inductor L2 and the diode D8 and a connection point between the primary winding of the leakage transformer T2 and the primary winding of the drive transformer CT. Are different. That is, in the present embodiment, the smoothing capacitor C0, the inductor L2, the diodes D7, D8,
The partial smoothing circuit 2 is constituted by the capacitor C6.
Note that the same components as those in the ninth embodiment are denoted by the same reference numerals, and description thereof is omitted.

The operation of the power supply according to the present embodiment will be briefly described below.

Assuming that the steady operation is performed, the switching element Q1 and the switching element Q2 are alternately turned on and off, and the second half of the period when the switching element Q2 is on is in the partial smoothing circuit 2-the capacitor C4-
A resonance current flows through the load circuit 1 through a path of the capacitor C3-the load circuit 1-the primary winding n of the drive transformer CT 1-the switching element Q2-the partial smoothing circuit 2, and the voltage across the capacitor C4 is output to the rectifier circuit DB. When the added voltage balances the voltage between both ends of the partial smoothing circuit 2, the AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-load circuit 1-primary winding n of drive transformer CT1-switching element Q2-rectifier circuit DB A resonance current flows through the load circuit 1 through the path of the AC power supply Vs (in this case, the input current is drawn from the AC power supply Vs, and the current value of the input current is
s) is proportional to the instantaneous value of s).

Next, when the switching element Q2 is turned off, the regenerative current from the leakage transformer T2 of the load circuit 1 is applied to the leakage transformer T2-the drive transformer CT.
Next winding n1-parasitic diode of switching element Q1-
The current flows through the path of the partial smoothing circuit 2-rectifier circuit DB-AC power supply Vs-rectifier circuit DB-diode D5-capacitor C3-leakage transformer T2. (Also at this time, the input current is drawn from the AC power supply Vs. The value is proportional to the instantaneous value of the AC power supply Vs).

Thereafter, when the regenerative current of the leakage transformer T2 becomes zero, the capacitors C3 to C3
-A capacitor C4-a switching element Q1-a primary winding n of the driving transformer CT-a load circuit 1-a resonance current flows through the load circuit 1 through the path of the capacitor C3, and a charge stored in the capacitor C4 when the switching element Q2 is turned on. When the charge of the capacitor C4 becomes zero, the resonance current flows from the capacitor C3 to the load circuit 1 through the path of the capacitor C3, the diode D6, the switching element Q1, the primary winding n of the drive transformer CT, the load circuit 1 and the capacitor C3. Flows.

Next, when the switching element Q2 is turned on, the regenerative current of the leakage transformer T2 of the load circuit 1 is changed to the leakage transformer T2-capacitor C3-diode D6-partial smoothing circuit 2-parasitic diode of the switching element Q2-drive transformer CT A regenerative current flows through the path of the primary winding n1-leakage transformer T2.

By repeating these series of operations, high-frequency power is supplied to the discharge lamp La. by the way,
Also in the circuit configuration shown in FIG. 13, since the filter circuit F for blocking high frequency is provided, the current input through the filter circuit F has a sinusoidal waveform substantially proportional to the voltage of the AC power supply Vs, and the harmonic current It is possible to obtain a relatively high input power factor with little distortion.

On the other hand, in the partial smoothing circuit 2, when the switching element Q2 is turned on, the AC power supply Vs-rectifier circuit DB-
Smoothing capacitor C0-Inductor L2-Diode D7
-The primary winding n of the driving transformer CT-the switching element Q2-the rectifier circuit DB-is charged through a path passing through the AC power supply Vs, and is smoothed at a voltage lower than the peak value of the output voltage of the rectifier circuit DB. When the peak value of the power supply voltage is lower than the voltage of the smoothing capacitor C0, power is supplied from the smoothing capacitor C0 to the inverter circuit INV.

The above operation is basically the same as the operation of the conventional configuration shown in FIG. 15, but in this embodiment,
As in the eighth embodiment, each secondary winding n2 of the driving transformer CT
1 and n22, respectively.
2 are connected in series, and when the power is turned on at a low temperature and the impedance of the discharge lamp La as a load is low, the impedance of each of the impedance elements Z1 and Z2 becomes high. (The voltage across the resistor R3 is a voltage determined by the voltage division of the impedance element Z1, the resistor R1, and the resistor R3, and the voltage across the resistor R4 is the voltage across the impedance element Z2 and the resistor R2.
The voltage determined by the voltage division of the switching element Q1 and the resistor R3) decreases, and as a result, the amplitude of the gate voltage (drive signal) of the switching elements Q1 and Q2 decreases, and the switching elements Q1 and Q2
Of the discharge lamp La can be prevented from being charged more than necessary, and the circuit components (smoothing capacitor C0, switching elements Q1, Q2
Etc.) can be reduced.

When the temperatures of the discharge lamp La and the drive transformer CT rise, the impedance of the discharge lamp La approaches the impedance at the time of steady lighting, so that the discharge lamp La operates in the output state at the time of steady lighting.

[0138]

The invention of claim 1 includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements alternately turned on and off at a high frequency. An inverter circuit for converting and supplying high-frequency power to a load, a smoothing capacitor connected in parallel to the series circuit of the two switching elements, and a rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted. A load transformer including a drive transformer, an LC resonance circuit, and the load for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit; A series circuit consisting of a DC cut capacitor is connected, and the printed circuit board is connected from one end of the longitudinal direction to the other end of the printed circuit board. Side, the rectifier circuit, the drive transformer and each switching element, and the inductance element of the load circuit are arranged in this order, and the drive transformer is arranged on a straight line connecting both switching elements in the width direction of the printed circuit board. Yes, even when the power is turned on at a low temperature and the impedance of the load is low, the drive transformer is heated by the radiant heat of the rectifier circuit, each switching element, the inductance element, etc., and the saturation magnetic flux density of the drive transformer is reduced. The operating frequency of each switching element shifts to the operating frequency for steady operation in a relatively short time due to the rapid turn-off of the switching element, thereby suppressing stress on circuit components due to a decrease in load impedance at low temperatures. There is an effect that can be.

The invention of claim 2 includes a rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements that are alternately turned on and off at a high frequency, and converts DC power to high-frequency power on the DC output side of the rectifier circuit. An inverter circuit for supplying high-frequency power to a load, a smoothing capacitor connected in parallel to the series circuit of the two switching elements, and a rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted. An inverter circuit includes a driving transformer and an LC resonance circuit for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit, and a load circuit including the load and a DC cut. And a series circuit composed of a capacitor for use in connection with the printed circuit board. , A rectifier circuit, a drive transformer and each switching element, and an inductance element of the load circuit are arranged in this order, and the drive transformer is arranged substantially at the center in the width direction of the printed circuit board, and both switching elements are arranged in the width direction of the printed circuit board. It is disposed on one end side, and even when the power is turned on at a low temperature and the impedance of the load is low, the drive transformer is heated by the radiant heat of the rectifier circuit, each switching element, the inductance element, etc. Since the saturation magnetic flux density of the switching element decreases, the turn-off of each switching element is accelerated, and the operating frequency of each switching element shifts to the operating frequency at the time of steady operation in a relatively short time. The resulting stress on circuit components can be suppressed There is an effect that.

The third aspect of the present invention includes a rectifying circuit for rectifying an AC power supply and a series circuit of two switching elements which are alternately turned on and off at a high frequency. The DC output side of the rectifying circuit converts DC power into high-frequency power. And an inverter circuit for supplying high-frequency power to the load, and a smoothing capacitor, which is connected in parallel to the series circuit of the two switching elements and is applied to the series circuit of the two switching elements only during a partial period of the output voltage of the rectifier circuit. And a rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted. The inverter circuit includes a connection point between the two switching elements and one of the direct currents of the rectifier circuit. A driving transformer for self-exciting control of the switching elements and an LC resonance circuit between the output terminal and the negative terminal including the load. A series circuit composed of a circuit and a DC cut capacitor is connected, and the printed circuit board includes a rectifier circuit, a drive transformer, each switching element, and an inductance of a load circuit from the input side at one end in the longitudinal direction to the output side at the other end. The components are arranged in the order of the elements, and the drive transformer is disposed on a straight line connecting the two switching elements in the width direction of the printed circuit board. Since the drive transformer is heated by radiation heat of the rectifier circuit, each switching element, the inductance element, and the like, the saturation magnetic flux density of the drive transformer decreases, the turn-off of each switching element is advanced, and the operating frequency of each switching element is relatively short. Will shift to the operating frequency during steady-state operation. There is an effect that it is possible to suppress the stress on the circuit components due to a decrease in the load impedance.

The invention of claim 4 includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements that are alternately turned on and off at a high frequency. And an inverter circuit for supplying high-frequency power to the load, and a smoothing capacitor, which is connected in parallel to the series circuit of the two switching elements and is applied to the series circuit of the two switching elements only during a partial period of the output voltage of the rectifier circuit. And a rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted. The inverter circuit includes a connection point between the two switching elements and one of the direct currents of the rectifier circuit. A driving transformer for self-exciting control of the switching elements and an LC resonance circuit between the output terminal and the negative terminal including the load. A series circuit composed of a circuit and a DC cut capacitor is connected, and the printed circuit board includes a rectifier circuit, a drive transformer, each switching element, and an inductance of a load circuit from the input side at one end in the longitudinal direction to the output side at the other end. The drive transformer is disposed substantially at the center in the width direction of the printed circuit board, and both switching elements are disposed at one end side in the width direction of the printed circuit board. Is turned on and the impedance of the load is low, the radiant heat of the rectifier circuit, each switching element, the inductance element, etc. heats the drive transformer and lowers the saturation magnetic flux density of the drive transformer, so that the turn-off of each switching element is accelerated. Operation when the operating frequency of each switching element is steady operation in a relatively short time Will be migrated to the wave number, there is an effect that it is possible to suppress the stress on the circuit components due to a decrease in the impedance of the load at low temperatures.

The fifth aspect of the present invention includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements which are alternately turned on and off at a high frequency. And a smoothing capacitor connected in parallel to the series circuit of the two switching elements, wherein the inverter circuit includes a connection point between the two switching elements and one of the rectifier circuits. A drive transformer for self-exciting control of the two switching elements, a series circuit including an LC resonance circuit, a load circuit including the load, and a DC cut capacitor are connected between the DC transformer and the DC output terminal. A primary winding connected between a connection point of the two switching elements and a load circuit; Line is connected to each of the above two switching devices so as to alternately turned on and off the two switching elements, which impedance element having a positive characteristic with respect to temperature is connected in parallel to the primary winding,
When the power is turned on at a low temperature and the impedance of the load is low, the ratio of the current flowing through the impedance element to the current flowing through the primary winding of the drive transformer becomes large, and as a result, each secondary winding of the drive transformer becomes Since the amplitude of the generated pulse voltage decreases and the oscillation frequency of each switching element increases, there is an effect that stress on circuit components due to a decrease in the impedance of the load at a low temperature can be suppressed.

The invention according to claim 6 includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements which are alternately turned on and off at a high frequency. The rectifier circuit converts DC power into high-frequency power on the DC output side. An inverter circuit that supplies high-frequency power to the load, and a voltage that includes a smoothing capacitor and is connected in parallel to the series circuit of the two switching elements and is applied to the series circuit of both switching elements only during a part of the output voltage of the rectifier circuit. A drive transformer for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit, and an LC resonance circuit. A series circuit including a circuit and a load circuit including the load and a DC cut capacitor is connected, and the drive transformer is A primary winding connected between a connection point of the two switching elements and a load circuit, and two secondary windings turning on and off the two switching elements alternately. And an impedance element having a positive characteristic with respect to temperature is connected in parallel to the primary winding, and when the power is turned on at a low temperature and the impedance of the load is low, The ratio of the current flowing in the impedance element to the current flowing in the primary winding of the drive transformer increases, and as a result, the amplitude of the pulse voltage generated in each secondary winding of the drive transformer decreases, and the oscillation of each switching element Higher frequency reduces stress on circuit components due to lower load impedance at low temperatures A.

According to a seventh aspect of the present invention, in the fifth or sixth aspect, the impedance element comprises a series circuit of a resistor and a temperature-sensitive element having a positive temperature coefficient. There is an effect that the impedance element can be prevented from affecting.

The invention of claim 8 includes a rectifier circuit for rectifying an AC power supply and a series circuit of two switching elements which are alternately turned on and off at a high frequency. And a smoothing capacitor connected in parallel to the series circuit of the two switching elements, wherein the inverter circuit includes a connection point between the two switching elements and one of the rectifier circuits. A drive transformer for self-exciting control of the two switching elements, a series circuit including an LC resonance circuit, a load circuit including the load, and a DC cut capacitor are connected between the DC transformer and the DC output terminal. A primary winding connected between a connection point of the two switching elements and a load circuit; A line is connected to each of the switching elements so as to alternately turn on and off the switching elements, and two impedance elements each having a negative characteristic with respect to temperature are connected in series to each secondary winding. When the power is turned on at a low temperature and the impedance of the load is low, the impedance of the impedance element connected in series to each of the secondary windings of the drive transformer is large, and the pulse voltage generated in each of the secondary windings of the drive transformer And the oscillation frequency of each switching element becomes higher, so that there is an effect that stress on circuit components due to a decrease in load impedance at a low temperature can be suppressed.

The ninth aspect of the present invention includes a rectifying circuit for rectifying an AC power supply and a series circuit of two switching elements which are alternately turned on and off at a high frequency, and converts DC power into high-frequency power at the DC output side of the rectifying circuit. An inverter circuit that supplies high-frequency power to the load, and a voltage that includes a smoothing capacitor and is connected in parallel to the series circuit of the two switching elements and is applied to the series circuit of both switching elements only during a part of the output voltage of the rectifier circuit. A drive transformer for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit, and an LC resonance circuit. A series circuit including a circuit and a load circuit including the load and a DC cut capacitor is connected, and the drive transformer is A primary winding connected between a connection point of the two switching elements and a load circuit, and two secondary windings turning on and off the two switching elements alternately. And two impedance elements each having a negative characteristic with respect to temperature and connected to each of the two switching elements, are connected in series to each of the secondary windings. Is low, the impedance of the impedance element connected in series to each secondary winding of the drive transformer is large,
Since the amplitude of the pulse voltage generated in the next winding is reduced and the oscillation frequency of each switching element is increased, there is an effect that stress on circuit components due to a decrease in load impedance at a low temperature can be suppressed. .

According to a tenth aspect of the present invention, in accordance with the eighth or ninth aspect of the present invention, the impedance element comprises a series circuit of a resistor and a temperature-sensitive element having a negative temperature coefficient. There is an effect that the impedance element can be prevented from affecting.

According to a twelfth aspect of the present invention, in the first to eleventh aspects of the present invention, the inverter circuit includes one end of a DC output terminal of the rectifier circuit to which a DC cut capacitor is connected and the two switching terminals. A diode connected in the forward direction to the rectifier circuit is connected between one end of the series circuit of elements and the input current from the AC power supply can flow at high frequency even when the voltage of the AC power supply is near zero crossing. Since the impedance element having an impedance as small as possible is connected in parallel to the diode, by providing a parallel circuit of the impedance element and the diode, even if the voltage of the AC power supply is near the zero crossing, the power supply from the AC power supply is The input current can flow at high frequency, and a small filter that blocks high frequency components There is an effect that it is possible to reduce the harmonic content of the input current to the extent that provided between the rectifier circuit.

According to a fourteenth aspect of the present invention, in the first to thirteenth aspects, since the load is a discharge lamp, an appropriate voltage across the smoothing capacitor can be obtained regardless of the state of the discharge lamp. There is an effect that necessary power can be supplied stably.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment, in which FIG. 1A is a circuit diagram, and FIG. 1B is an explanatory diagram of an arrangement of circuit components on a printed circuit board.

FIG. 2 is an explanatory diagram of an arrangement of circuit components on a printed circuit board according to a second embodiment.

3A and 3B are diagrams illustrating a third embodiment, in which FIG. 3A is a circuit diagram, and FIG. 3B is an explanatory diagram of an arrangement of circuit components on a printed circuit board.

FIG. 4 is an explanatory diagram of an arrangement of circuit components on a printed circuit board according to a fourth embodiment.

FIG. 5 is a circuit diagram showing a fifth embodiment.

FIG. 6 is a configuration diagram of a main part of the above.

FIG. 7 is an operation explanatory diagram of the above.

FIG. 8 is a circuit diagram showing a sixth embodiment.

FIG. 9 is a circuit diagram showing a seventh embodiment.

FIG. 10 is a circuit diagram showing an eighth embodiment.

FIG. 11 is a configuration diagram of a main part of the above.

FIG. 12 is a circuit diagram showing a ninth embodiment;

FIG. 13 is a circuit diagram showing a tenth embodiment.

FIG. 14 is a circuit diagram showing a conventional example.

FIG. 15 is a circuit diagram showing another conventional example.

[Explanation of symbols]

 Reference Signs List 1 load circuit 30 printed circuit board Vs AC power supply DB rectifier circuit D1 to D4 diode INV inverter circuit Q1, Q2 switching element CT drive transformer La discharge lamp C0 smoothing capacitor

Claims (14)

[Claims] 1. A rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements that are alternately turned on and off at a high frequency. Circuit, a smoothing capacitor connected in parallel to the series circuit of the two switching elements, and a rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted. A drive transformer for self-exciting control of the two switching elements between a connection point of the two switching elements and one DC output terminal of the rectifier circuit;
A series circuit including a C resonance circuit, a load circuit including the load, and a DC cut capacitor is connected. The printed circuit board includes a rectifier circuit, a drive transformer, And each switching element, the inductance element of the load circuit are arranged in order,
In addition, the power supply device is characterized in that the drive transformer is arranged on a straight line connecting both switching elements in the width direction of the printed circuit board. 2. A rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements that are alternately turned on and off at a high frequency. Circuit, a smoothing capacitor connected in parallel to the series circuit of the two switching elements, and a rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted. A drive transformer for self-exciting control of the two switching elements between a connection point of the two switching elements and one DC output terminal of the rectifier circuit;
A series circuit including a C resonance circuit, a load circuit including the load, and a DC cut capacitor is connected. The printed circuit board includes a rectifier circuit, a drive transformer, And each switching element, the inductance element of the load circuit are arranged in order,
In addition, a drive transformer is provided substantially at the center in the width direction of the printed circuit board, and both switching elements are provided at one end side in the width direction of the printed circuit board. 3. A rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements that are alternately turned on and off at a high frequency. And a smoothing capacitor, which is connected in parallel to the series circuit of the two switching elements, and smoothes the voltage applied to the series circuit of the two switching elements only during a partial period of the output voltage of the rectifier circuit. A rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted, wherein the inverter circuit is provided between a connection point between the two switching elements and one DC output terminal of the rectifier circuit. A drive transformer and an LC resonance circuit for self-exciting control of both the switching elements and a load circuit including the load and a DC cutoff The printed circuit board is provided with a rectifier circuit, a drive transformer, each switching element, and an inductance element of a load circuit in this order from the input side at one end in the longitudinal direction to the output side at the other end. And a drive transformer disposed on a straight line connecting the two switching elements in the width direction of the printed circuit board. 4. A rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements that are alternately turned on and off at a high frequency. And a smoothing capacitor, which is connected in parallel to the series circuit of the two switching elements, and smoothes the voltage applied to the series circuit of the two switching elements only during a partial period of the output voltage of the rectifier circuit. A rectangular printed circuit board on which components of the rectifier circuit and the inverter circuit are mounted, wherein the inverter circuit is provided between a connection point between the two switching elements and one DC output terminal of the rectifier circuit. A drive transformer and an LC resonance circuit for self-exciting control of both the switching elements and a load circuit including the load and a DC cutoff The printed circuit board is provided with a rectifier circuit, a drive transformer, each switching element, and an inductance element of a load circuit in this order from the input side at one end in the longitudinal direction to the output side at the other end. A power transformer, wherein the drive transformer is disposed substantially at the center in the width direction of the printed circuit board, and both switching elements are disposed at one end side in the width direction of the printed circuit board. 5. A rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements that are alternately turned on and off at a high frequency. And a smoothing capacitor connected in parallel to the series circuit of the two switching elements, wherein the inverter circuit includes a connection point between the two switching elements and one DC output terminal of the rectifier circuit. A drive transformer for self-exciting control of the two switching elements, an LC resonance circuit, and a series circuit including a load circuit including the load and a DC cut capacitor are connected, and the drive transformer includes two secondary windings. A primary winding is connected between the connection point of the two switching elements and the load circuit, and two secondary windings are connected to the two switches. A power supply device comprising an impedance element connected to each of the switching elements so as to alternately turn on and off the switching element, and having a positive characteristic with respect to temperature, connected in parallel to the primary winding. 6. A rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements that are alternately turned on and off at a high frequency. And a partial smoothing circuit which includes a smoothing capacitor and is connected in parallel with the series circuit of the two switching elements and smoothes the voltage applied to the series circuit of both switching elements only during a part of the output voltage of the rectifier circuit. A drive transformer for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit, an LC resonance circuit, and the load. A series circuit consisting of a load circuit and a DC cut capacitor is connected, and the drive transformer is
Having two secondary windings, a primary winding connected between a connection point of the two switching elements and a load circuit,
Two secondary windings are connected to the switching elements so as to alternately turn on and off the switching elements, and an impedance element having a positive characteristic with respect to temperature is connected in parallel to the primary winding. Power supply device characterized. 7. The power supply device according to claim 5, wherein the impedance element comprises a series circuit of a resistor and a temperature-sensitive element having a positive temperature coefficient. 8. A rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements which are alternately turned on and off at a high frequency. And a smoothing capacitor connected in parallel to the series circuit of the two switching elements, wherein the inverter circuit includes a connection point between the two switching elements and one DC output terminal of the rectifier circuit. A drive transformer for self-exciting control of the two switching elements, an LC resonance circuit, and a series circuit including a load circuit including the load and a DC cut capacitor are connected, and the drive transformer includes two secondary windings. A primary winding is connected between the connection point of the two switching elements and the load circuit, and two secondary windings are connected to the two switches. A power supply device, wherein two impedance elements each having a negative characteristic with respect to temperature and connected to each of the switching elements so as to alternately turn on and off the switching elements are connected in series to each secondary winding. . 9. A rectifier circuit for rectifying an AC power supply, and a series circuit of two switching elements which are alternately turned on and off at a high frequency. And a partial smoothing circuit which includes a smoothing capacitor and is connected in parallel with the series circuit of the two switching elements and smoothes the voltage applied to the series circuit of both switching elements only during a part of the output voltage of the rectifier circuit. A drive transformer for self-exciting control of the switching elements between a connection point of the switching elements and one DC output terminal of the rectifier circuit, an LC resonance circuit, and the load. A series circuit consisting of a load circuit and a DC cut capacitor is connected, and the drive transformer is
Having two secondary windings, a primary winding connected between a connection point of the two switching elements and a load circuit,
Two secondary windings are connected to the switching elements so as to alternately turn on and off the switching elements, and two impedance elements each having a negative characteristic with respect to temperature are connected in series to each secondary winding. A power supply device comprising: 10. The power supply device according to claim 8, wherein the impedance element comprises a series circuit of a resistor and a temperature-sensitive element having a negative temperature coefficient. 11. The power supply device according to claim 1, wherein each of said switching elements comprises a MOSFET. 12. The rectifier circuit according to claim 1, wherein the inverter circuit is connected between one end of a DC output terminal of the rectifier circuit to which a DC cut capacitor is connected and one end of a series circuit of the two switching elements. A diode in the forward direction is connected, and an impedance element having an impedance small enough to allow an input current from the AC power supply to flow at a high frequency even when the voltage of the AC power supply is near zero cross is connected in parallel to the diode. The power supply device according to any one of claims 1 to 11, wherein: 13. The power supply device according to claim 12, wherein said impedance element is a capacitor. 14. The power supply device according to claim 1, wherein the load is a discharge lamp.