JPH1197189A - Power supply device and control method for output voltage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage resonance power supply device which can be embodied in a small construction and at a low cost and which is equipped with enhanced reliability. SOLUTION: When an On signal for a fluorescent lamp is fed to a control circuit 4, a current transformer 63 of a resonant condition sensing circuit 62 senses the current flowing in a transistor 60 and converts it into a voltage, and the obtained voltage is fed to a zenor diode 65. When the voltage remains as not attaining the zenor voltage, a transistor 66 is turned off, and an On-Off control part 45 puts off the fifth PWM signal. If thereafter the voltage value exceeds the zenor voltage, the transistor 66 is turned on, and the fifth PWM signal is put On. This operating cycle is repeated until the fluorescent lamp 47 lights up.

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 and an output voltage control method, and more particularly, to a voltage resonance type power supply device that generates a plurality of output loads with a single transformer and an output voltage for controlling the output voltage. Control method.

[0002]

2. Description of the Related Art Conventionally, as a power supply of this kind,
As shown in FIG. 6, a control voltage section 130 including a low-voltage flyback circuit 101, a low-voltage forward output circuit 102, a high-voltage output circuit 103, and a fluorescent lamp lighting circuit 104, a voltage resonance switch 106, and the voltage resonance switch 106 There is known a power supply device having a transformer 105 interposed between the control voltage unit 130 and the transformer 105 and generating an output voltage required for each of the output circuits 101 to 104 of the control voltage unit 130 by the transformer 105. ing.

In the power supply device, when an AC power supply 107 is applied, power is supplied to a control circuit 109 via a power supply transformer 108. Then, a first pulse-width modulation (hereinafter, referred to as “PWM”) signal is output from the control circuit 109 to which power is supplied, and the first PWM signal is subjected to voltage resonance via the drive transformer 110. The signal is supplied to the switch 106.

The voltage resonance switch 106 comprises a primary transistor 111, a drive circuit 112 for driving the primary transistor 111, and a resonance capacitor 113 connected in parallel with the primary transistor 111. Are driven by the first PWM signal supplied to the drive circuit 112 via the drive transformer 110. This allows the voltage resonance switch 106
Is transmitted to the control voltage unit 130 via the output load supply transformer 105.

That is, the low-voltage flyback output circuit 10
1, the first PWM signal is detected by the first detection circuit 114, and the first PWM signal is detected by the control circuit 109.
The M signal is controlled to have a constant voltage.

In the low voltage forward output circuit 102, a second PWM signal is generated in synchronization with the first PWM signal, and the driving circuit 115 is controlled based on the second PWM signal output from the control circuit 109. The forward output control transistor 116 is driven via the control circuit. Then, the second PWM signal is detected by the second detection circuit 117, and the second PWM signal is detected by the control circuit 109.
The signal is controlled to have a constant voltage.

In the high-voltage output circuit 103, the high-voltage control transistor 1 is output via the drive circuit 118 based on the third PWM signal output from the control circuit 109.
19 is driven. Then, the third PWM signal is detected by the third detection circuit 120 and the control circuit 10
9, the third PWM signal is controlled to have a constant voltage.

Further, in the fluorescent lamp lighting circuit 104, the preheat control transistor 1 is driven by the fourth PWM signal output from the control circuit 109 via the drive circuit 121.
22 is driven. Then, the control circuit 109 outputs a fifth PWM signal based on the light amount detected by the light amount sensor (not shown) while performing the filament preheating of the fluorescent lamp 124 via the preheating transformer 123, and controls the driving circuit 125. The on / off control of the fluorescent lamp control transistor 126 is performed via the control signal.

[0009]

However, since the above-mentioned conventional power supply device is of the voltage resonance type, the low-voltage flyback output is the main control target. Therefore, after the fluorescent lamp ON signal is input to the control circuit 109, if the fluorescent lamp non-lighting state continues for a certain period of time and the fluorescent lamp output becomes the load open state, the current limiting choke coil 127 The resonance frequency decreases under the influence of the inductance. That is, when the fluorescent lamp control transistor 126 is turned on, a constant current flows through the fluorescent lamp lighting circuit 104, in which case the capacitance C of the resonance capacitor 113 of the voltage resonance switch 106 and the inductance of the secondary winding Although resonance occurs at the resonance frequency uniquely determined by L, when the fluorescent lamp ON signal is input to the control circuit 109, the fluorescent lamp control transistor 126 is kept off for a moment. When the off state lasts for a certain period of time, the output of the fluorescent lamp lighting circuit 104 becomes a load open state, and the resonance frequency is reduced by the influence of the inductance of the current limiting choke coil 127.

Since the voltage supplied to the flyback output circuit 101 decreases due to such a decrease in the resonance frequency, the output voltage obtained at the normal resonance frequency cannot be maintained. Therefore, the control circuit 109 controls the first PWM to compensate for the decrease in the output voltage.
Control is performed so as to increase the on-time of the on-off time ratio of the signal, and finally to increase the on-time of the first PWM signal until the on-off time ratio corresponds to the decrease in the resonance frequency. .

On the other hand, when the fluorescent lamp 124 is turned on with the ON time extended, the influence of the inductance of the current limiting choke coil 127 described above is eliminated, thereby returning to the resonance state at the normal resonance frequency. However, since it takes time for the first PWM signal to return to the on / off time ratio corresponding to the normal resonance frequency, it is not possible to immediately return to the desired on / off time ratio. When the fluorescent lamp 124 is turned on in a state where the on-time is increased and the resonance voltage is increased, the primary-side transistor 11 is turned on.
An unnecessary load is applied between the emitter and the collector of No. 3.

FIG. 7 shows the time width (on time) Ton of the current pulse when the primary transistor 111 (driven by the first PWM signal) is turned on when the fluorescent lamp is turned on.
Time width (off time) Tof of the voltage pulse at the time of switch off
f.

For example, when the voltage resonance switch 106 is driven at a normal resonance frequency, the primary-side transistor 111 performs a switching operation with an off time Toff0 and an on time Ton0. In this case, the fluorescent lamp lighting circuit 104 is controlled by the constant voltage V0 and the constant current I0.
Is controlled, but when the fluorescent lamp ON signal is input to the control circuit 109, the resonance frequency decreases for the above-described reason. In the case of the voltage resonance switch 106, since the off time Toff is fixed and the on time Ton is changed, the on time Ton1 is gradually increased as compared with the off time Toff1, and the fluorescent lamp is in a state where the on time Ton1 is increased. 1
24 lights up. That is, in a state where the peak value of the resonance voltage increases and jumps to the voltage value V1, the fluorescent lamp 124
Lights up. After that, the resonance frequency sharply rises due to the lighting of the fluorescent lamp 124, and the resonance state returns to the normal state. However, it takes time for the on-time Ton to return to the time corresponding to the resonance frequency. Continues to rise and jumps up to the voltage value VN. Therefore, an unnecessary load is applied between the emitter and the collector of the primary transistor 111. Therefore, it is necessary to use a switching element having a high withstand voltage for the primary transistor 111, which increases the size and cost of the device. There was a problem of inviting.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. By controlling the amount of current flowing through a fluorescent lamp lighting circuit in accordance with the resonance state of a voltage resonance switch, the power supply can be reduced in size and cost can be reduced. It is an object of the present invention to provide a power supply device and a control method of an output voltage capable of realizing high reliability and improving reliability.

[0015]

Means for Solving the Problems To achieve the above object, of the power supply device according to the present invention, the invention according to claim 1 is:
A drive having a voltage resonance switch, and a control voltage unit including a plurality of circuit blocks including at least a flyback output circuit and a fluorescent lamp lighting circuit, and obtained based on an output signal output from the flyback output circuit A power supply device that drives the voltage resonance switch by a signal and generates a plurality of output voltages by a single transformer interposed between the voltage resonance switch and the control voltage unit. It is characterized by comprising resonance state detecting means for detecting a state, and control means for controlling an input signal inputted to the fluorescent lamp lighting circuit in accordance with a detection result of the resonance state detecting means.

[0016] In the output voltage control method according to the present invention, the invention according to claim 8 includes a plurality of circuit blocks including at least a flyback output circuit and a fluorescent lamp lighting circuit, wherein the flyback is provided. A method for controlling a voltage resonance switch by driving a voltage resonance switch with a drive signal obtained based on an output signal output from an output circuit and generating an output voltage in the plurality of circuit blocks by a single transformer, wherein the voltage resonance switch A resonance state of the switch is detected, and an input signal input to the fluorescent lamp lighting circuit is controlled according to the detected resonance state.

The other features of the present invention will be apparent from the following description of embodiments of the present invention.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an electric circuit diagram showing an embodiment of the power supply device according to the present invention.

The power supply device receives a predetermined voltage (5) from the AC power supply 1 via the AC power supply 1 and the power supply transformer 2.
V) a power generation unit 3 for generating a power supply;
And a control circuit 4 for controlling an output voltage signal (first to fifth PWM signals) to be a constant voltage and a first PWM signal output from the control circuit 4. A voltage resonance switch 6 driven and controlled via a drive transformer 5 and a control voltage section 8 to which a predetermined load is supplied from the voltage resonance switch 6 via an output load supply transformer 7 are provided. In addition, 9 is a rectifier diode and 10 is a smoothing capacitor.

The control voltage section 8 includes a low voltage flyback output circuit 11, a low voltage forward output circuit 12, a high voltage output circuit 13, and a fluorescent lamp lighting circuit 14.

The low-voltage flyback output circuit 11 has a first detection circuit 15 for detecting a first PWM signal and outputting it to the control circuit 4, a rectifying diode 16 and a smoothing capacitor 17. .

The low voltage forward output circuit 12 includes a second detection circuit 18 for detecting a second PWM signal, a forward output control transistor 19, and a drive circuit for issuing a drive command to the forward output control transistor 19. 20, a smoothing capacitor 21, and a choke coil 22
And a plurality of rectifying diodes 23 and 24. The low-voltage forward output circuit 12 and the low-voltage flyback output circuit 11 are connected to each other via a connection line 25.

The high-voltage output circuit 13 includes a third detection circuit 26 for detecting a third PWM signal, a high-voltage control transistor 27, a drive circuit 28 for issuing a drive command to the high-voltage control transistor 27, and a high-voltage output circuit 13. A resistor 29 for limiting a current value flowing through the voltage output circuit 13, double rectifying diodes 30 and 31, a plurality of high-voltage capacitors 32 and 33,
34.

Further, the control circuit 4 responds to the power input unit 35 to which the first to third PWM signals are input from the control voltage unit 8 and the energy required by the load such as the type of the load and the driving state. A reference voltage setting unit 36 for setting a desired reference voltage, a first comparator 37 for comparing the first PWM signal with a predetermined reference voltage set by the reference voltage setting unit 36, and a first comparator A second register 39 for comparing the second PWM signal and / or the third PWM signal with a predetermined reference voltage set by the reference voltage setting unit 36; And the second
The second register 40 for storing the comparison result of the comparator 39 and the first register 38 based on the comparison result of the first register 38.
A first PWM signal generation circuit 41 for generating a PWM signal (drive signal), and a second PWM signal generation circuit for generating second and third PWM signals in accordance with the contents stored in the second register 42, respectively. Circuit 42 and a third PWM signal generation circuit 43, and a fourth PWM having a predetermined on / off time ratio.
A fourth PWM signal generating circuit 44 for generating a signal, and controlling on / off of a fifth PWM signal according to a fluorescent lamp on / off signal input to the control circuit 4 or a resonance state of the resonance voltage switch 6 A fifth PWM on / off control unit (hereinafter, referred to as an “on / off control unit”) 45 to perform a fifth PWM based on a control command from the on / off control unit 45.
And a PWM signal generation circuit 46 for generating a signal.

The fluorescent lamp lighting circuit 14 includes a fluorescent lamp 47, a transformer 48 for preheating the fluorescent lamp 47, a driving transistor 49 for driving the transformer 48, and an output from the control circuit 4. 4th PW to be done
A driving circuit 50 that issues an operation command to the driving transistor 49 based on the M signal, a lighting current control transistor 51 for controlling the lighting current of the fluorescent lamp 47, and a fifth PWM signal output from the control circuit 4. A driving circuit 52 for issuing an operation command to the lighting current control transistor 51 based on the above, a current limiting choke coil 53 of the fluorescent lamp 47, and a coupling interposed between the choke coil 53 and the fluorescent lamp 47. It has a capacitor 54 and a plurality of lighting current cut-off diodes 55, 56, 57, 58.

The voltage resonance switch 6 includes a primary transistor 60, a drive circuit 61 for driving the primary transistor 60, and a resonance capacitor 59 connected in parallel with the primary transistor 60.

Reference numeral 62 denotes a resonance state detection circuit. The resonance state detection circuit 62 converts a current value detected by the current transformer 63 into a voltage value. A resistor 67 for
A Zener diode 65, a resonance state control transistor 66 which is turned on when a voltage value supplied to the Zener diode 65 exceeds a predetermined Zener voltage, is interposed between the current transformer 63 and the Zener diode 65. Rectifier diode 64 and resistor 6 connected to the collector of resonance state control transistor 66.
And 8.

The power generating unit 3 includes a rectifying diode 69, a three-terminal regulator 70, and a smoothing capacitor 7.
1, 72 and the like.

In the power supply device configured as described above, when an AC voltage is applied by the AC power supply 1, the reference power supply VDD (5 V) is supplied to the control circuit 4 via the power supply transformer 2 and the power generation unit 3. Is done. And
When the reference power supply VDD is supplied to the control circuit 4, a first PWM signal is output from the control circuit 4 and supplied to the voltage resonance switch 6 as a drive signal. That is, the first PWM signal is supplied to the drive circuit 61 via the drive transformer 5, whereby the primary side transistor 60 is driven, and the desired energy is supplied to the control voltage section 8 via the output load supply transformer 7. Is done.

Then, in the low-voltage flyback output circuit 11, which is the main control target, the first PWM signal is detected by the first detection circuit 14 and input to the power supply input section 35 of the control circuit 4. Next, the first PWM signal from the power input unit 35 and a predetermined reference voltage are compared by the first comparator 37, and the error voltage is stored in the first register 38. After that, the first PWM signal generation circuit 46 modulates the on / off time ratio of the pulse width based on the storage result of the first register 38, and outputs the first PWM signal to the drive transformer 5, whereby The switching operation of the primary transistor 60 is controlled such that the first PWM signal supplied to the low-voltage flyback output circuit 11 has a constant voltage.

In the low voltage forward output circuit 12, the second PWM signal is synchronized with the generation of the first PWM signal.
A WM signal is generated, and the second P
The WM signal is detected and input to the power input unit 35 of the control circuit 4. Then, the second from the power input unit 35
Is compared with a predetermined reference voltage by a second comparator 39, and the error voltage is stored in a second register 40. Next, the second PWM signal generation circuit 42 modulates the on / off time ratio of the pulse width based on the storage result of the second register 40 and supplies the modulated signal to the drive circuit 20, thereby supplying the low voltage forward output circuit 12. The switching operation of the forward output control transistor 19 is controlled such that the second PWM signal has a constant voltage.

Further, in the high voltage output circuit 13,
The third PWM signal is detected by the third detection circuit 26 and input to the power supply input unit 35 of the control circuit 4.
Then, the third PWM signal from the power input unit 35 and the predetermined reference voltage are compared by the second comparator 39, and the error voltage is stored in the second register 40. Next, the third PWM signal generation circuit 43 modulates the on / off time ratio of the pulse width based on the storage result of the second register 40 and supplies the modulated pulse width to the drive circuit 28, whereby the high voltage output circuit 13
The switching operation of the high-voltage control transistor 27 is controlled such that the third PWM signal supplied to the transistor becomes a constant voltage.

In the fluorescent lamp lighting circuit 14, the driving transistor 49 is driven via the driving circuit 50 by the fourth PWM signal output from the control circuit 4 at a predetermined on / off time ratio, and the preheating transformer is driven. 48 preheats the filament of the fluorescent lamp 47.

The lighting control of the fluorescent lamp 47 is performed as follows. That is, when the fluorescent lamp ON signal is input to the control circuit 4, the fifth PWM signal is turned on, and the resonance state detection circuit 62 outputs the current transformer 63
Detects the value of the current flowing through the primary-side transistor 60, converts the detected current value into a voltage value via the resistor 67, and supplies the voltage value to the Zener diode 65. Then, the non-lighting state of the fluorescent lamp 47 continues beyond the predetermined time tn, and when the voltage value supplied to the Zener diode 65 does not reach the Zener voltage, the resonance state control transistor 66 continues to be in the off state, 5 is turned off. Then, again, the current transformer 63
Detects the value of the current flowing through the primary-side transistor 60, converts the current value into a voltage value, and when the voltage value exceeds the Zener voltage, turns on the resonance-state control transistor 66, whereby the fifth PWM The signal turns on. And
The above control is repeated until the fluorescent lamp 47 is turned on.

FIG. 2 is a flowchart showing a method for controlling the output voltage.

In step S1, it is determined whether or not the fluorescent lamp ON signal has been input to the control circuit 4. When the control circuit 4 detects the fluorescent lamp ON signal, the fifth PWM signal is turned on (step S2). It is determined whether a zero cross signal has been detected (step S3). Here, the zero-cross signal is a signal indicating that the voltage input to the Zener diode 65 reaches the Zener voltage and the resonance state is normal. If no zero-cross signal is detected, it is determined whether or not the non-detection time of the zero-cross signal has reached “T0 (> tn)” (step S4). Then, when the non-detection time has not reached T0, it waits until it reaches, and when the non-detection time has reached T0, the fifth PWM signal is turned off (step S5). Then
In step S6, it is determined whether or not the zero cross signal has been detected, and at the same time, it is determined whether or not the detection time T1 has become longer than a predetermined time tn. If the answer to step S6 is affirmative (Yes), the fifth PWM signal is turned on (step S7). Then, in step S8, it is determined whether or not the zero-cross signal is detected again. If the answer is negative (No), it is determined that the resonance state is not normal and there is still a rebound of the resonance voltage. S
8 is repeated. On the other hand, when the answer to step S8 is affirmative (Yes), it is determined that the resonance state has become normal, and the process ends.

FIG. 3 is a time chart showing a driving state of the primary side transistor 60 (driven by the first PWM signal) until the fluorescent lamp is turned on.

When the voltage resonance switch 6 is driven in a normal resonance state, the first PWM signal has an off time Toff
0 and the ON time Ton0, the primary side transistor 60 performs a switching operation. In this case, the fluorescent lamp lighting circuit 14 is controlled by the constant voltage V0 and the constant current I0.

On the other hand, when the fluorescent lamp on signal is input to the control circuit 109, the first PWM signal is turned on to maintain the output voltage of the low-voltage flyback output circuit 11, which is the main control voltage, at a predetermined voltage. Although the time increases, in the present embodiment, the above-mentioned zero-cross signal non-detection time T0 is slightly larger than the on-time Ton0.
The fifth PW at the time when on2 has elapsed (T0> tn)
The M signal is turned off, and then the fifth PWM signal is turned on at the time of detection of the zero-cross signal (the detection time T1) where the on time Ton of the first PWM signal is again Ton0, and then the fifth PWM signal is turned on. The on / off control of the PWM is repeated, and after the resonance state becomes normal and the zero cross signal is detected, the fluorescent lamp 47 is turned on.

As described above, in the present embodiment, when the fifth PWM signal is turned on simultaneously with the input of the fluorescent lamp ON signal, when the resonance state detecting circuit 62 detects an abnormality in the resonance state, the fifth PWM signal is output. It turns off and waits for the resonance state to become normal. After confirming that the resonance state has become normal, the fifth PWM signal is turned on again to turn on the fluorescent lamp 47. It is possible to avoid lighting in a state where the on-time of the signal is increased, and it is possible to suppress the rebound of the resonance voltage at the time of lighting the fluorescent lamp as in the related art. Therefore, the voltage applied between the collector and the emitter of the primary side transistor 60 when the fluorescent lamp is turned on can be suppressed, and as a result, the primary side transistor 60
It is possible to reduce the size of the switching element used in the power supply device, and to realize high reliability, small size, and low cost of the power supply device.

FIG. 4 is a main part electric circuit diagram showing a second embodiment of the present invention. In the second embodiment, a resonance state detecting circuit 73 includes a secondary winding 74, It is composed of a rectifying diode 75, a comparator 76, and a plurality of resistors 77 to 80.

In the second embodiment, the secondary winding 74
And a resonance voltage is detected by the resistors 77 and 78, and the resonance voltage is input to a comparator 76, and is compared with a reference voltage determined by a voltage dividing ratio between the resistor 79 and the resistor 80.
The on / off control unit 45 is controlled in accordance with the comparison result by That is, when the resonance voltage has not reached the reference voltage, the comparator 76 outputs a low-level signal to the on / off control unit 45 to turn off the fifth PWM signal. When the voltage exceeds the voltage, the control to turn on the fifth PWM signal is performed by the fluorescent lamp 47.
The operation is repeated until lights up.

As described above, the resonance voltage is detected by the secondary winding 74 and the resistors 77 and 78, and the fifth PWM signal is turned on / off in accordance with the resonance voltage.
As in the first embodiment, it is possible to suppress the rebound of the resonance voltage when the fluorescent lamp is turned on, and the primary-side transistor 6
0 can be prevented from being supplied with overvoltage and overcurrent, thereby making it possible to reduce the size of the switching element, and to achieve high reliability, downsizing, and cost reduction of the power supply device. .

FIG. 5 is a main part electric circuit diagram showing a third embodiment of the present invention. In the third embodiment, a resonance state detecting circuit 81 includes a rectifying diode 83 and a comparator. The resonance state detection circuit 81 is connected to the flyback output circuit 12 via a connection line 89.

In the third embodiment, the resonance voltage is detected by the secondary winding of the flyback output circuit 12 and the resistor 85, and the resonance voltage is input to the comparator 84, and the resistor 8
The on / off control unit 45 is compared with a reference voltage determined by a voltage dividing ratio between the resistor 7 and the resistor 88 and according to a comparison result by the comparator 84. That is, when the resonance voltage has not reached the reference voltage, the comparator 84
A low-level signal is output to the off control unit 45, and the fifth PW
The M signal is turned off, and when the resonance voltage exceeds the reference voltage after a predetermined time, the control for turning on the fifth PWM signal is repeated until the fluorescent lamp 47 is turned on.

As described above, the resonance voltage is detected by the secondary winding of the flyback output circuit 12 and the resistor 85, and the fifth PWM signal is turned on / off in accordance with the resonance voltage. As in the first and second embodiments,
The rebound of the resonance voltage when the fluorescent lamp is turned on can be suppressed, and the overvoltage and the overcurrent can be prevented from being supplied to the primary-side transistor 60. Therefore, the size of the switching element can be reduced, and the power supply can be reduced. High reliability, miniaturization and low cost of the device can be realized.

[0048]

As described above in detail, according to the power supply apparatus and the output voltage control method of the present invention, it is not necessary to use a switching element having a high withstand voltage between the collector and the emitter. Cost reduction and high reliability can be achieved.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing one embodiment (first embodiment) of a power supply device according to the present invention.

FIG. 2 is a flowchart illustrating an output voltage control method according to the present invention.

FIG. 3 is a time chart for explaining an output voltage control method according to the present invention.

FIG. 4 is a main part electric circuit diagram showing a second embodiment of the power supply device according to the present invention.

FIG. 5 is a main part electric circuit diagram showing a third embodiment of the power supply device according to the present invention.

FIG. 6 is an electric circuit diagram showing a conventional example of a power supply device.

FIG. 7 is a time chart for explaining a conventional output voltage control method.

[Explanation of symbols]

Reference Signs List 6 voltage resonance switch 7 output load supply transformer (transformer) 8 control voltage section 11 low voltage flyback output circuit (flyback output circuit) 45 on / off control section (control means) 62, 73, 81 resonance state detection circuit (resonance) State detecting means) 63 current transformer

Claims (14)

[Claims] An output signal output from the flyback output circuit includes a voltage resonance switch, and a control voltage unit including a plurality of circuit blocks including at least a flyback output circuit and a fluorescent lamp lighting circuit. A power supply device that drives the voltage resonance switch with a drive signal obtained based on the voltage, and generates a plurality of output voltages with a single transformer interposed between the voltage resonance switch and the control voltage unit. It is characterized by comprising resonance state detection means for detecting a resonance state of the voltage resonance switch, and control means for controlling an input signal input to the fluorescent lamp lighting circuit according to a detection result of the resonance state detection means. And power supply. 2. The power supply device according to claim 1, wherein said input signal is constituted by a pulse width modulation signal. 3. The resonance state detection means includes: a current detection means for detecting a current flowing through the voltage resonance switch; a voltage conversion means for converting the current detected by the current detection means into a voltage; 3. The power supply device according to claim 1, further comprising: an off-state setting unit that sets the input signal to an off state when the voltage value converted by the control unit does not reach a predetermined voltage. 4. The power supply according to claim 3, wherein said current detecting means is a current transformer. 5. The resonance state detection means includes: a resonance voltage detection means for detecting a resonance voltage; a comparison means for comparing a resonance voltage detected by the resonance voltage detection means with a predetermined reference voltage; 3. The power supply device according to claim 1, further comprising an off-state setting unit that sets the input signal to an off state when the predetermined reference voltage is not reached. 6. The power supply device according to claim 5, wherein said resonance voltage detecting means includes at least a secondary winding of said transformer. 7. The power supply device according to claim 5, wherein said resonance state detecting means is electrically connected to said flyback output circuit. 8. A voltage resonance switch having a plurality of circuit blocks including at least a flyback output circuit and a fluorescent lamp lighting circuit, wherein the voltage resonance switch is driven by a drive signal obtained based on an output signal output from the flyback output circuit. In the output voltage control method of driving and generating an output voltage to the plurality of circuit blocks by a single transformer, a resonance state of the voltage resonance switch is detected, and the fluorescent lamp is operated in accordance with the detected resonance state. A method for controlling an output voltage, comprising controlling an input signal input to a lighting circuit. 9. The output voltage control method according to claim 8, wherein said input signal is constituted by a pulse width modulation signal. 10. Detecting a current flowing through the voltage resonance switch, converting the current into a voltage, and then setting the input signal to an off state when the converted voltage does not reach a predetermined voltage. 10. The output voltage control method according to claim 8, wherein: 11. The method according to claim 10, wherein the current is detected by a current transformer. 12. After the resonance voltage is detected, the detected resonance voltage is compared with a predetermined reference voltage, and when the resonance voltage does not reach the predetermined reference voltage, the input signal is set to an off state. 10. The method according to claim 8, wherein:
The described output voltage control method. 13. The output voltage control method according to claim 12, wherein a resonance voltage is detected by a secondary winding of the transformer. 14. The output voltage control method according to claim 12, wherein a resonance voltage is detected by a secondary winding in a flyback output circuit of the transformer.