JP2008022668A - Power supply device using half-bridge circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device using a half-bridge circuit which can be used for stabilizers, inverters or the like which are improved in output control dynamic properties by applying variable frequency and pulse-width control. <P>SOLUTION: The power supply device comprises a line voltage detection means for detecting the voltage of an input power supply transmitted to a load; a line voltage conversion amplifying means for comparing the voltage detected by the line voltage detection means with a reference voltage to output the voltage corresponding to the difference; a pulse width conversion means for outputting a pulse; a dead time control means for generating a first pulse corresponding to high side and a second pulse corresponding to low side as the pulse provided by the pulse width conversion means to output the pulses, so as to allow the first pulse and the second pulse to have respectively different pulse widths, rising and falling times; and a drive means for driving the power supply to be supplied to the load by the first pulse and the second pulse at a constant current condition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply device using a half-bridge circuit, and more specifically, applied to a ballast, an inverter, and the like, and a half-bridge drive circuit for maintaining power factor compensation, a low crest factor, and a constant output. The present invention relates to a power supply device using

In general, an electronic ballast or inverter applied to a lamp serves to adjust a current so that an overcurrent does not flow by converting a normal power supply frequency into a high frequency. The ballast described above employs various methods of power factor compensation circuits for current consumption, lifetime improvement, and product reliability.

  As an example, a method for realizing a high power factor and a low crest factor by changing a frequency using a diode power factor compensation circuit is proposed.

However, since this method does not use an expensive power factor compensation dedicated integrated circuit, power factor compensation and a low crest factor can be implemented at a low cost, but there is a problem due to the large frequency variable range.

Specifically, when the frequency is increased, the efficiency of the resonant circuit is decreased, so that the efficiency of the ballast is decreased and the frequency change is widened, so that the EMI noise problem is increased and the switching power loss of the switching element is increased. And the energy supplied to the filament is increased, reducing the life of the lamp tube and reducing the efficiency of the ballast.

And when trying to control the output with only the frequency variable, the output control dynamic characteristics are low, so not only the setting of the feedback circuit for control becomes difficult, but also the efficiency characteristics of the ballast are poor, so it is practically used Is difficult.

In particular, when the input voltage fluctuates, changes in power consumption, crest factor, filament power, and the like increase, and the difference from the target characteristic value increases.

On the other hand, the method of using the power factor compensation integrated circuit instead of the diode power factor compensation circuit is expensive because the power factor compensation dedicated integrated circuit is expensive. Since it was large, there was a difficulty in increasing the size.

An object of the present invention is to provide a power supply device using a half-bridge circuit that can be used for a ballast, an inverter, or the like that has improved output control dynamic characteristics by applying variable frequency and pulse width control.

Another object of the present invention is to provide a power supply device using a half-bridge circuit that can be used for a ballast or inverter having a high power factor, a constant output, and a low crest factor characteristic without requiring a separate high power factor circuit. There is to do.

Still another object of the present invention is to provide a power supply apparatus using a half bridge circuit that can be used for a ballast, an inverter, etc., which has improved power conversion efficiency to prevent shortening of lamp tube life and improved light conversion efficiency. There is.

A power supply device using a half-bridge circuit that rectifies an AC power supply and transmits it to a load according to the present invention is detected by the line voltage detection means for detecting the voltage of the input power supply transmitted to the load, and the line voltage detection means. The line voltage conversion amplification means for comparing the measured voltage with a reference voltage and outputting a voltage corresponding to the difference, and a pulse having a variable pulse width corresponding to the output level of the line voltage conversion amplification means As a pulse provided from the pulse width conversion means and the pulse width conversion means, a first pulse corresponding to the high side and a second pulse corresponding to the low side are generated and output, and the first pulse and the second pulse are generated. Dead time control means for outputting the pulse width, rising time and falling time different from each other, and the load by the first pulse and the second pulse. Drive means for driving the power supplied to the power source in a constant current state.

Here, the line voltage detecting means transmits a low-pass filter that smoothes the input power supply and converts it into a DC voltage, and if the voltage of the low-pass filter is less than a certain value, the line voltage conversion amplifying means. A line voltage detector.

The line voltage detector drives a shutdown unit that further outputs an output signal having a logic value if the voltage of the low-pass filter is equal to or higher than a certain value.

The line voltage converting and amplifying means outputs a comparator that outputs the voltage detected by the line voltage detecting means in comparison with a constant voltage, and an output value of the comparator combined with a divided reference voltage. And a line voltage conversion amplification unit that compares a voltage provided from the voltage distribution unit with a feedback voltage of a voltage supplied to the lamp and outputs a signal corresponding to the difference.

The voltage distribution unit is configured such that a dimming control voltage is applied instead of the reference voltage.

And a frequency generation unit that provides the pulse width conversion unit with a variable frequency corresponding to the output level of the line voltage conversion amplification unit, and the pulse width conversion unit is provided from the frequency generation unit. And a pulse having a variable pulse width corresponding to the output level of the line voltage conversion amplification means.

Then, the frequency generator and the line voltage conversion amplification means are controlled at the time of initial startup, enabling output of a high frequency and a maximum pulse width at the initial stage of power supply application, and then gradually decreasing the frequency after a certain time has elapsed. A soft start timer for stopping the operation is further provided.

The dead time control means includes a delay means for outputting the first pulse to which a first dead time obtained by delaying an output rising point of the pulse width conversion means by a predetermined time, and an output of the pulse width conversion means. And a delay means for outputting the second pulse to which a second dead time obtained by delaying a rising time of the inverted signal by a predetermined time is applied.

The driving means includes a high-side driver that outputs a driving signal for the high side as a first pulse, a low-side driver that outputs a driving signal for the low side as a second pulse, and an output of the high-side driver. A first switching element that switches a high side of the AC power source that is transmitted to the load; and a second switching element that switches the low side of the AC power source that is transmitted to the load by the output of the low side driver.

The power supply further includes a high power factor circuit for controlling the power factor of the input power source transmitted to the load, and the load is configured by CCF1.

INDUSTRIAL APPLICABILITY According to the present invention, it can be applied to a half-bridge fluorescent lamp ballast and a CCF1 inverter circuit, and the output control dynamic characteristics can be improved by controlling the pulse width while varying the frequency of the lower band. .

This makes it possible to stably control the constant output and the tube current CF in a very low state corresponding to a wide range of input voltage fluctuations even under conditions of a positive high power factor rectifier circuit having a valley voltage (Va11ey). And inverter can be implemented.

In addition, because it can realize very high dynamic characteristics while reducing the frequency variable width, the circuit can operate under optimal resonance conditions, so that the light conversion efficiency of the ballast or inverter can be improved, and the fluorescent ballast ballast In this case, the change in energy flowing through the filament is very small, so that the life of the tube can be extended.

In addition, when an existing half-bridge circuit is used, the control dynamic characteristics are deteriorated when there are voltage fluctuations and tube deviations. Therefore, the current CF value of the tube is remarkably deteriorated, the constant power is incomplete, the frequency change width is large, the change of the current flowing through the filament is also large, the light conversion efficiency is poor, and the life of the tube is shortened. I can't.

The present technology can also be used for dimming of fluorescent lamps or CCF1, and according to this, stable dimming can be controlled even at a very low illuminance that cannot be compared with existing control methods.

Embodiments according to the present invention will be described below with reference to the accompanying drawings.
The embodiment according to the present invention has a configuration that realizes variable frequency and pulse width control. That is, the pulse width of the signal provided to the load is variable depending on the level of the voltage supplied from the power supply, and the frequency of the signal provided selectively to the load is simultaneously variable. This is a technology that provides a constant output to the load.

FIG. 1 shows an embodiment in which the embodiment of the present invention is applied to a ballast. Referring to this, a rectifier circuit 10 has a bridge-coupled configuration of four diodes, and rectifies and outputs an _AC power supply VAC. .

A path for driving the load lamp 36 of the rectifier circuit 10 and a control path for always maintaining the output provided to the load constant are provided.

  First, the output of the rectifier circuit 10 for driving the load lamp 36 is provided to the high-side transistor M1 and the low-side transistor M2 connected in series. The high-side transistor M1 and the low-side transistor M2 transmit the current provided from the rectifier circuit 10 to the load lamp 36 while performing cross-switching, and the power provided to the lamp 36 is controlled by adjusting the respective switching times.

The configuration for adjusting the switching of the high-side transistor M1 and the low-side transistor M2 corresponds to a control path for constantly maintaining the output provided to the load.

A node is formed between the high side transistor M1 and the low side transistor M2, and a connection node between the auxiliary power supply 34 and the lamp 36 connected in series is connected to this node. The load resistor R1 is inserted on the ground side of the lamp 36, and the sensing resistor RS is inserted on the ground side of the low-side transistor M2. The load resistor R1 has a configuration for detecting the amount of current supplied to the lamp 36 as a voltage, and the sensing resistor RS is for detecting the amount of current flowing through the low-side transistor M2 as a voltage.

On the auxiliary power supply 34 side, an output DS from the shutdown unit 42 is input and a Vref unit 421 that controls activation of Vref, a UV1O unit 422, a parallel start connected resistor RS and a capacitor CV, and are connected in the reverse direction. A diode D4 is inserted, and a Zener diode DZ is connected in parallel with them. The diode D4 and the Zener diode DZ are for controlling the back electromotive force and the ripple. Here, the UV1O unit 422 is for performing an under voltage lockout. Specifically, the UV1O unit 422 starts at a high Vcc at the time of initial startup, and the capacitor CV is charged when started. Charges are discharged instantly. At that time, Vcc may drop instantaneously. In order to prevent the circuit operation from being affected even if Vcc drops instantaneously, the voltage at which the circuit operation is stopped is set to about 1.5 V to 2 V lower than the starting voltage, thereby facilitating the initial starting. This is equivalent to a comparator with hysteresis.

On the other hand, the output of the rectifier circuit 10 is provided to the low-pass filter (1PP) 12 in a control path for constantly maintaining the output provided to the load.

The low-pass filter 12 smoothes the AC voltage supplied by rectifying the radio wave from the rectifier circuit 10 and outputs a DC voltage corresponding to the AC voltage. The DC voltage is provided to the line voltage detector 14.

The line voltage detector 14 has an output signal DA having a logic value and an output signal DB having a linear value.

That is, when the output of the low-pass filter 1PF is above a certain level, the line voltage detector 12 detects this and generates an output signal DA for shutting down the entire circuit and provides it to the NOR gate 40. Conversely, when the output of the low-pass filter 1PF begins to drop below a certain level, an output signal DB having a corresponding linear value is output to the plus terminal of the comparator 16.

Specifically, the line voltage detector 12 is configured as shown in FIG. 2, and referring to this, the output of the low-pass filter 12 is input to the high level detector 142 and the low level detector 144, respectively. The high level detector 142 outputs a corresponding signal DA when the input voltage is above a certain level, and the low level detector 144 is input when the input voltage falls below a certain level. The voltage is transmitted to the linear amplifier 148. Accordingly, the linear amplifier 148 outputs the output signal DB in a state where the output is adjusted while the input voltage is maintained in a linear state.

The reference voltage provided to the line voltage conversion amplifier EA is gradually reduced by the output signal DB, and as a result, the power transmitted to the load is reduced.

On the other hand, referring to FIG. 1, the comparator 16 is configured such that a predetermined voltage VB is applied to the negative terminal, and the output signal DB of the line voltage detector 14 is compared and amplified and provided to the voltage distribution unit 18. .

The voltage distribution unit 18 includes resistors R1 and R2 connected in parallel to a node connected to the plus terminal of the line voltage conversion amplification unit EA. The voltage distribution unit 18 adjusts the output of the comparator 16 to the divided reference voltage Vref, and the line voltage Provided to the plus terminal of the conversion amplification unit EA.

The operation of the line voltage conversion amplification unit EA is controlled by the soft start timer 26, and provides an output to the frequency generation unit (VCO) 20 and the pulse width conversion unit (PWM) 20, so that the frequency generation unit 20 and the line voltage Applicability of variable frequency is selected by inserting a switch 24 that can be arbitrarily operated by the user between the conversion amplification units EA.

Then, when the output is transmitted from the line voltage conversion amplification unit EA, the frequency generation unit 20 generates a frequency signal corresponding to the level of the input voltage and provides it to the pulse width conversion unit 20, from the line voltage conversion amplification unit EA. If the output is not transmitted, a fixed frequency signal is generated and provided to the pulse width converter 20.

Then, the pulse width conversion unit 20 outputs a pulse having a corresponding frequency by the frequency signal provided from the frequency generation unit 23, and the pulse width corresponds to the voltage level provided from the line voltage conversion amplification unit EA. Output variable pulse.

The soft start timer 26 is a circuit for controlling the frequency so that power is gradually transmitted at the time of initial startup. The soft start timer 26 is controlled so that it can output at a high frequency and a maximum pulse width at the initial stage of power application, and then gradually decreases the frequency for a certain time. After the elapse of time, the operation of the soft start timer 26 is stopped, the feedback circuit is operated, and the entire closed circuit is controlled. The state for the operation can be described as shown in FIG.

On the other hand, the dead time control unit 28 controls the signal output from the pulse width conversion unit 20 so that the dead times d1 and d2 exist between the high side and the low side, and the dead time control unit 28 The configuration is as shown in FIG.

That is, the dead time control unit 28 delays the rising time of the output signal PWM_IN of the pulse width conversion unit 20 by d1, an inverter 284 that inverts the output signal PWM_IN of the pulse width conversion unit 20 and outputs the signal PWM_IN_B, A delay 283 that delays the falling point of the output signal of the inverter 284 by d2.

The operation of the above-described dead time control unit 28 will be described with reference to FIG.
The pulse width conversion unit 20 triggers the frequency signal provided from the frequency generation unit 20 based on the output of the line voltage conversion amplification unit EA, outputs a pulse having a predetermined pulse width, and outputs the line voltage conversion amplification unit EA. Depending on the level, the pulse width conversion unit 20 correspondingly determines the width of the pulse width and outputs it.

That is, as shown in FIG. 5b, the dead time is variable between HO and 1O, although the output pulse width of the HO from the pulse width conversion unit 20 is varied by the output voltage of the line voltage conversion amplification unit EA. The time interval (DEAD TIME) must be maintained.

Specifically, referring to FIG. 5a, the output PWM_IN of the pulse width converter 20 is converted into a pulse H_DRV for driving the high side by a delay 282. The pulse H_DRV is delayed by d1 compared with the rising time of the signal PWM_IN at the rising time, and the falling time has the same pulse width.

The output PWM_IN of the pulse width converter 20 is inverted by the inverter 284 to the signal PWM_1N_B, and the inverted signal PWM_1N_B is converted by the delay 286 into a pulse 1_DRV for driving the low side. The rising time is the same as that of the pulse 1_DRV, and has a pulse width that is delayed by d2 compared with the signal PWM_1N_B.

Here, the delay 282 and the delay 284 have delay times for determining dead times (DEAD TIME) d1 and d2, and have delay times similar to each other.

As described above, if the output of the line voltage conversion amplification unit EA is variable as shown by V1 to V3 in FIG. 6, the dead time control unit 280 causes the line voltage to be changed by each lower pulse in FIG. A pulse having a pulse width corresponding to the output level of the conversion amplification unit EA is output. At this time, the dead time is the same even if the pulse width is changed.

The dead time is for maintaining a constant time interval in order to prevent the high-side transistor M1 and the low-side transistor M2 from being turned on simultaneously.

FIG. 6 illustrates changes in the pulses output from the dead time control unit 28 due to changes in the output of the line voltage conversion amplification unit EA corresponding to the fixed frequency.

In addition to this, when the current output from the rectifier circuit 10 is reduced and the input voltage is lowered, the frequency is also variable and the dynamic characteristics are improved.

Specifically, as shown in FIGS. 7a to 7c, the frequency can be varied and the output change of the line voltage conversion amplification unit EA can simultaneously correspond to variously adjust the pulse.

FIG. 7a shows the case where the pulse width is narrow when the frequency is high and the output of the line voltage conversion amplifier EA is low, and FIG. 7b shows the case where the frequency is intermediate and the output of the line voltage conversion amplifier EA is also intermediate. FIG. 7c shows a case where the pulse width is wide when the frequency is low and the output of the line voltage conversion amplifier EA is high. Referring to FIGS. 7a to 7c, it can be seen that the ratio of the pulse width between the high side and the low side is changed depending on the frequency.

The pulses as described above are input to the high-side driver 30 and the low-side driver 32, respectively, and the high-side transistor M1 and the low-side transistor M2 are turned on at different timings, and the lamp 36 eventually maintains a constant output. become.

In the present invention, in order to effectively supply load power even when the AC line input voltage is low, the duty of the pulse for the high side of the half-bridge driving circuit is fixed to 50% as in a general half-bridge circuit. It can be changed to 50% or more depending on the situation. The pulse relationship between the high side (upper pulse) and the low side (lower pulse) is shown in FIG. 7d.

As described above, when the current provided from the rectifier circuit 10 to the load lamp 36 fluctuates, the turn-on time of the high-side transistor M1 and the low-side transistor M2 becomes variable correspondingly, so that the constant output for the lamp 36 is maintained. Is guaranteed.

On the other hand, when an abnormality occurs in the load lamp 36 and an overcurrent flows through the transistor, this is detected by the resistor RS, so that the circuit operation is stopped. The circuit operation is controlled by a shutdown unit 42 that receives the output of the NOR gate 40. The VREF unit 421 deactivates Vref by the signal CS output from the shutdown unit 42 to stop the oscillation, and the auxiliary power supply is linked to it. Is stopped and current supply to the load is stopped.

When the ambient temperature rises, this is detected by the heat detector 38, and the circuit operation is stopped as described above.

Further, when an overcurrent flows due to an abnormality in the load, this is detected by the resistor R1, and the start determination unit 43 transmits a corresponding signal to the shutdown unit 42, and then the circuit operation is stopped as described above. Carried out.

In the present invention described above, a ballast to which a simple high power factor circuit, which is a rectification method having a Valley voltage, is applied can be applied as shown in FIG.

FIG. 8 is different from the simple high power factor circuit 800 in a part of the configuration on the load side, and the other components are the same as those in the embodiment of FIG. Here, since the simple high power factor circuit 800 has a known configuration including a plurality of diodes D1, D2 and D3, a plurality of capacitors C1 and C2, and a resistor R1, a detailed description of the operation will be omitted.

The output of the bridge diode 10 by the simple high power factor circuit 800 is as shown in FIG. 9a, whereby the output waveform of the line voltage conversion amplifier EA is as shown in FIG. 9b.

That is, in the section where the input voltage is high, the frequency is high and the pulse width is small, and in the section where the input voltage is low, the frequency is low and the pulse width is large, so that the constant output is maintained. The output voltage of the conversion amplification unit EA is reverse to the input as shown in FIG. 9b.

Further, in the embodiment of the present invention, when the pressure power supply voltage falls below a certain level, the line voltage detector gradually reduces the output voltage to prevent overcurrent from flowing to the driving transistor, as shown in FIG. 10a. Be controlled.

This is because when the output of the line voltage detector 14 starts to become lower than the reference voltage of the comparator 16, the output current of the comparator increases in inverse proportion to the voltage at which the output current decreases, and the feedback of the line voltage conversion amplifier EA is increased. Since the voltage at the positive terminal, which is the reference voltage, is lowered, the output is also lowered accordingly.

In the embodiment according to the present invention, the pulse width and the frequency are varied over the entire section to control and output the power, so that the high power factor is realized and the AC power is constant output over the entire section of 180V to 300V. A lamp current crest factor of .5 or less can be achieved, and the filament power can be controlled within +/− 10%.

In other words, when the change in the input voltage is small, the output can be controlled mainly by controlling the pulse width. When the change in the input voltage is large, the frequency variable range is widened to increase the frequency along the input voltage. In addition, the pulse width is linked and moved so that a constant output can always be maintained even for a wide range of input voltage fluctuations.

The corresponding drawing is shown in FIG. 10b.
Referring to FIG. 10b, A shows the output waveform of the line voltage conversion amplifier when the frequency fluctuation range is reduced and the pulse width is changed and the output is controlled when the input voltage fluctuation range is small. B is a waveform diagram showing the output of the line voltage conversion amplification unit EA when the frequency fluctuation range is increased and the pulse width is changed to control the output when the input voltage fluctuation range is large.

In addition, the present invention can be applied to a dimming ballast, and an embodiment applied to the dimming ballast includes a dimming control voltage instead of the reference voltage in the voltage distributor 18 of FIG. It is the structure which provides.

When the reference voltage of the line voltage conversion amplification unit EA is changed, the output changes accordingly. Therefore, when the dimming control voltage is applied to the resistor R1 that determines the reference voltage of the line voltage conversion amplifier EA for dimming, the output current is controlled by the applied voltage, so that the brightness of the lamp can be adjusted.

In order to reduce the illuminance, the reference voltage of the line voltage conversion amplification unit EA is lowered to reduce the feedback amount. In this case, the frequency is increased and the pulse width is reduced at the same time as compared with the method in which only the frequency is increased and the illuminance is reduced. The energy transmitted to the filament can be effectively limited. In addition, since the amount of change in frequency is very small, low illuminance dimming is possible without deviating from the optimum resonance condition, so it is very advantageous to reduce the illuminance.

Further, the embodiment according to the present invention can be applied to a CCF1 inverter circuit using a rectification simple high power factor circuit having a valley voltage as shown in FIG. 12, and the operation for this is the same as each of the embodiments described above. Abbreviated.

In each of the embodiments described above, the voltage and current characteristics of the input contrast load are evaluated as shown in FIGS. 13a to 13c.

Specifically, FIG. 13a is a waveform diagram of input current and voltage, FIG. 13b is a waveform diagram of output voltage, and FIG. 13c is a waveform diagram of output current. Referring to FIGS. 13a to 13c, it can be seen that the embodiments of the present invention can stabilize the output voltage and current, and can realize a high power factor and a low crest factor.

It is a circuit diagram which shows the preferable Example of the electric power supply apparatus using the half bridge circuit applied to the ballast which concerns on this invention. It is a detailed block diagram which shows an example of the line voltage detector of the Example of FIG. It is a wave form diagram for demonstrating control of the soft start timer which concerns on this invention. It is a detailed block diagram which shows an example of the dead time control part of the Example of FIG. 5a and 5b are waveform diagrams for explaining the operation of the dead time control unit. It is a wave form diagram for demonstrating the pulse width change corresponding to the output level fluctuation | variation of a line voltage conversion amplification part. 7A to 7D are waveform diagrams for explaining the pulse width change corresponding to the frequency and the output fluctuation of the line voltage conversion amplification unit. It is a circuit diagram which shows the other Example of this invention to which a simple high power factor circuit is applied. 9a and 9b are rectified outputs and output waveform diagrams of the corresponding line voltage conversion amplifier in the embodiment of FIG. FIG. 10A is a waveform diagram illustrating a change in the reference input terminal EA + of the line voltage conversion amplification unit and a corresponding change in the output power when the input power supply voltage of the embodiment falls below a predetermined level. These are waveform diagrams showing the output waveform of the line voltage conversion amplification unit corresponding to the input voltage fluctuation. It is a circuit diagram which shows the further another Example of this invention to which the light control voltage is applied. FIG. 6 is a circuit diagram showing another embodiment of the present invention applied to a CCF1 inverter circuit using a rectifying simple high power factor circuit having a valley voltage. 13A to 13C are waveform diagrams for evaluating the voltage and current characteristics of the input contrast load.

Claims (11)

In a power supply device using a half bridge circuit that rectifies an AC power supply and transmits it to a load,
Line voltage detection means for detecting the voltage of the input power source transmitted to the load;
A line voltage conversion amplification means for comparing the voltage detected by the line voltage detection means with a reference voltage and outputting a voltage corresponding to the difference;
Pulse width conversion means for outputting a pulse having a variable pulse width corresponding to the output level of the line voltage conversion amplification means;
As the pulse provided from the pulse width conversion means, a first pulse corresponding to the high side and a second pulse corresponding to the low side are generated and output, and the first pulse and the second pulse have different pulse widths and rising edges, respectively. dead time control means for outputting to have a (rising) and falling time point;
A power supply device using a half-bridge circuit, comprising: a driving unit configured to drive a power source supplied to the load by the first pulse and the second pulse in a constant current state. The line voltage detecting means is
A low-pass filter that smoothes the input power supply and converts it to a DC voltage;
The power supply using the half-bridge circuit according to claim 1, further comprising: a line voltage detector that transmits the low-pass filter voltage to the line voltage conversion amplification means if the voltage of the low-pass filter is less than a predetermined value. apparatus. The power supply apparatus using the half-bridge circuit according to claim 2, wherein the line voltage detector further outputs an output signal having a logic value if the voltage of the low-pass filter is equal to or higher than a certain value. The line voltage conversion amplification means includes:
A comparator that outputs the voltage detected by the line voltage detection means in comparison with a constant voltage;
A voltage distribution unit that outputs the output value of the comparator together with a divided reference voltage;
2. A line voltage conversion amplification unit that compares a voltage provided from the voltage distribution unit with a feedback voltage of a voltage supplied to the lamp, and outputs a signal corresponding to the difference. A power supply device using the half-bridge circuit described in 1.   The power supply apparatus using a half-bridge circuit according to claim 4, wherein the voltage distribution unit is supplied with a dimming control voltage instead of a reference voltage. A frequency generator for providing a variable frequency corresponding to the output level of the line voltage conversion amplification means to the pulse width conversion means;
The pulse width conversion unit outputs a pulse having a frequency of a signal provided from the frequency generation unit and having a variable pulse width corresponding to an output level of the line voltage conversion amplification unit. A power supply apparatus using the half-bridge circuit according to claim 1. The frequency generator and the line voltage conversion amplification means are controlled at the time of initial startup to enable output of a high frequency and a maximum pulse width at the initial stage of power application, and then gradually decrease the frequency and operate after a certain period of time. The power supply apparatus using the half-bridge circuit according to claim 6, further comprising a soft start timer that stops. The dead time control means includes
Delay means for outputting the first pulse to which a first dead time obtained by delaying an output rising time of the pulse width conversion means by a predetermined time is applied;
A delay means for inverting the output of the pulse width conversion means and outputting the second pulse to which a second dead time obtained by delaying the rising time of the inverted signal by a predetermined time is specified. A power supply apparatus using the half-bridge circuit according to claim 1. The driving means includes
A high side driver that outputs a drive signal for the high side as a first pulse;
A low-side driver that outputs a drive signal for the low side as a second pulse;
A first switching element for switching a high side of an AC power source transmitted to the load by an output of the high side driver;
The power supply device using the half bridge circuit according to claim 1, further comprising: a second switching element that switches a low side of an AC power source that is transmitted to the load by an output of the low side driver. The power supply apparatus using a half-bridge circuit according to claim 1, further comprising a high power factor circuit that controls a power factor of an input power source transmitted to the load. The power supply apparatus using a half-bridge circuit according to any one of claims 1 to 9, wherein the load is a cold cathode fluorescent lamp (CCF1).

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