JP2001286161A - Power supply unit using piezoelectric transformer and information processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power source using a piezoelectric transformer, which enables to monitor the output of the piezoelectric transformer and to make its dimension small without adding a sophisticated circuit or the like. SOLUTION: The piezoelectric transformer 21 has input terminals 21a, 21b, an output terminal 21c and an output monitor terminal 21d. An AC power source 22 is connected between the input terminal 21a, 21b and an AC output voltage generated between the output terminal 21c and a ground line GND is supplied to a load 23. The piezoelectric transformer has the input terminals 21a, 21b on the upper face and the lower face of an input element 25 and the output terminal 21c in the front face of an output element 26. An output monitor pole 27 in a strip is formed on one face of the output element 26 at a position apart a prescribed distance from the output terminal 21c, and on this pole 27 an output monitor terminal 21d is provided. An output control of the piezoelectric transformer is made by obtaining a sufficiently low voltage comparing with the output voltage of the load as the supervisory voltage from the output monitor terminal 21d.

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 a piezoelectric transformer and an information processing device using the power supply device.

[0002]

2. Description of the Related Art In recent years, information processing apparatuses having a display device using a cold-cathode tube as a light source have been spurred to be made thinner, and a power supply device (C
FL inverters) are no exception, and miniaturization is inevitable. In order to reduce the size of the power supply device, a device using a piezoelectric transformer as a transformer has recently been considered.

FIG. 6 shows a basic configuration of a power supply device using a conventional piezoelectric transformer 1. The piezoelectric transformer 1 includes input terminals 1a and 1b and an output terminal 1c,
An AC power supply 2 of, for example, about 30 V and about 60 kHz is supplied between the input terminals 1a and 1b, and the output terminal 1c is connected to the ground line G.
An AC output voltage generated between the ND and the ND is supplied to a load 3 such as a cold cathode tube.

The piezoelectric transformer 1 has a drive frequency-boost ratio characteristic as shown in FIG. In this drive frequency-boost ratio characteristic, the drive frequency at which the boost ratio peaks is the resonance frequency fo of the piezoelectric transformer 1, and when the drive frequency changes in a direction away from the resonance frequency, the boost ratio of the piezoelectric transformer 1 decreases. . Further, as shown in FIG. 8, the step-up ratio of the piezoelectric transformer 1 is the load impedance R
The resonance frequency is also increased and the boost ratio is increased as the load impedance RL is increased.

FIG. 9 shows a specific configuration example of a power supply device using the piezoelectric transformer 1 described above. FIG.
In the figure, reference numeral 11 denotes a power transformer, and a DC power supply 10 of, for example, about 5 V is supplied to a primary winding thereof via a switching element 12. The switching element 12 is turned on / off by an output control unit 16 which will be described in detail later.
The DC voltage supplied from the DC power supply 10 is converted into an AC voltage and supplied to the power transformer 11. The power transformer 11 boosts a supply voltage of, for example, 5 V to a voltage of 30 V, and supplies the voltage to the input terminals 1 a and 1 b of the piezoelectric transformer 1.
In this case, one input terminal 1b is connected to the ground line GND. Then, an AC output voltage generated between the output terminal 1 c of the piezoelectric transformer 1 and the ground line GND is supplied to the load 3.

The output terminal 1c of the piezoelectric transformer 1
Between output voltage and ground line GND
3 are connected. The voltage dividing resistor 13 includes a resistor 13a and a resistor 13b connected in series. The AC voltage divided by the voltage dividing resistors 13a and 13b is rectified by the rectifying element 14 and supplied to the voltage detecting unit 15. The voltage detector 15 includes an integrator, integrates the pulsating voltage rectified by the rectifier 14, compares it with a reference voltage, and inputs the comparison result to the output controller 16.

The output control section 16 turns on / off the switching element 12 at a frequency corresponding to the DC voltage supplied from the voltage detection section 15, and drives the piezoelectric transformer 1 at a frequency higher than the resonance frequency fo shown in FIG. ing. The output control unit 16 lowers the driving frequency of the piezoelectric transformer 1 so that the output voltage increases when the output voltage detected by the voltage detection unit 15 is lower than the target value, and when the output voltage is higher than the target value. The driving frequency of the piezoelectric transformer 1 is increased so that the output voltage decreases, and the output voltage is maintained at a target value. In the above power supply device, particularly when the output is in a no-load state, the output impedance viewed from the piezoelectric transformer 1 becomes infinite, and the boost ratio of the piezoelectric transformer 1 also increases as shown in FIG. This means that an excessive voltage is output from the output terminal 1c of the piezoelectric transformer 1 and an excessive stress is applied to the piezoelectric transformer 1. In addition, there is a risk that the dielectric breakdown due to the discharge from the high voltage portion to the low voltage portion of the piezoelectric transformer 1 and that the transformer is damaged due to the application of excessive stress. The output control unit 16 monitors the output voltage in order to avoid the danger as described above, and controls the drive frequency of the piezoelectric transformer 1 so that an appropriate voltage is always output.

[0008]

In the above-mentioned conventional power supply device, voltage dividing resistors 13a and 13b are provided between the output terminal 1c of the piezoelectric transformer 1 and the ground line GND in order to monitor the output of the piezoelectric transformer 1. The divided voltage is applied to the rectifier 14
And input to the voltage detection unit 15. Since a high voltage output from the piezoelectric transformer 1 is applied to the voltage dividing resistors 13a and 13b, the voltage dividing resistors 13a and 13b
In this state, discharge easily occurs from b to other low-voltage parts. For this reason, conventionally, it is necessary to arrange the voltage dividing resistors 13a and 13b on the power supply substrate so as to prevent discharge from occurring from the voltage dividing resistors 13a and 13b to other low voltage parts, and to reduce the size of the substrate by insulation measures or the like. This is an adverse effect.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to monitor the output of a piezoelectric transformer without adding a complicated circuit and the like, and to provide a power supply device using a piezoelectric transformer which can be downsized. It is an object to provide an information processing device using the power supply device.

[0010]

According to a first aspect of the present invention, in a power supply device using a piezoelectric transformer, an output monitoring electrode is formed on an output element of the piezoelectric transformer, and this electrode has a proportional relationship with an output voltage. By providing an output monitoring terminal for extracting a voltage lower than the output voltage, which is proportional to the output voltage, as described above, wherein an output monitoring terminal for extracting a voltage lower than the output voltage is provided. The output voltage can be monitored without providing a voltage dividing resistor for monitoring the output outside the piezoelectric transformer, miniaturizing the power supply unit and minimizing the exposure of the high voltage section of the piezoelectric transformer to the outside. Safety can be improved.

According to a second aspect of the present invention, in a power supply device using a piezoelectric transformer, an output monitoring electrode is formed on an output element, and an output for extracting a voltage which is proportional to the output voltage and is lower than the output voltage is formed on the electrode. A piezoelectric transformer having a monitoring terminal, an overvoltage detection unit that compares a monitoring voltage output from the output monitoring terminal with a set value, and outputs an overvoltage detection signal when the monitored voltage exceeds a set value; Output stopping means for stopping the output of the piezoelectric transformer in response to an overvoltage detection signal output from the overvoltage detecting means. According to the above configuration, the output of the piezoelectric transformer can be stopped by detecting an abnormality in the output voltage based on the monitoring voltage output from the output monitoring terminal, and the circuit can be prevented from being damaged. Further, the output voltage can be monitored without providing a voltage dividing resistor for monitoring the output outside the piezoelectric transformer, so that the power supply device can be downsized and the safety can be improved.

According to a third aspect of the present invention, in a power supply device using a piezoelectric transformer, an output monitoring electrode is formed on an output element, and an output for extracting a voltage lower than the output voltage, which is proportional to the output voltage, is formed on the electrode. A piezoelectric transformer having a monitoring terminal, and output control means for controlling a driving frequency of the piezoelectric transformer in accordance with a monitoring voltage output from the output monitoring terminal and holding an output of the piezoelectric transformer constant. It is characterized by. According to the above configuration, the output of the piezoelectric transformer can be kept constant by using the monitoring voltage output from the output monitoring terminal, and since there is no need to provide a voltage dividing resistor for output monitoring outside the piezoelectric transformer, The power supply device can be reduced in size and safety can be improved.

According to a fourth aspect of the present invention, in a power supply device using a piezoelectric transformer, an output monitoring electrode is formed on an output element, and an output for extracting a voltage lower than the output voltage, which is proportional to the output voltage, is formed on the electrode. A piezoelectric transformer having a monitoring terminal, and an output control for controlling a driving frequency of the piezoelectric transformer in accordance with a monitoring voltage output from the output monitoring terminal or a load current of the piezoelectric transformer, and maintaining a constant output of the piezoelectric transformer. Means, a monitoring voltage output from the output monitoring terminal, and a set value, and an overvoltage detection means for outputting an overvoltage detection signal when the monitoring voltage exceeds the set value; and an output from the overvoltage detection means. Output stopping means for stopping the output of the piezoelectric transformer in response to an overvoltage detection signal. According to the above configuration,
The output of the piezoelectric transformer can be kept constant according to the monitoring voltage or the load current output from the output monitoring terminal, and the output of the piezoelectric transformer can be stopped by detecting an abnormality in the output voltage based on the monitoring voltage. Further, since it is not necessary to provide a voltage dividing resistor for monitoring the output outside the piezoelectric transformer, the power supply device can be downsized and the safety can be improved.

According to a fifth aspect of the present invention, in a power supply device using a piezoelectric transformer, a voltage dividing resistor for dividing an output voltage is formed on an outer surface of the piezoelectric transformer, and a voltage divided by the voltage dividing resistor is taken out. An output monitoring terminal is provided. According to the above configuration, the voltage divided by the voltage dividing resistor formed on the outer surface of the piezoelectric transformer can be taken out from the output monitoring terminal, so that a voltage dividing resistor for output monitoring is not provided outside the piezoelectric transformer. The output voltage can be monitored. In addition, by integrating the voltage dividing resistor on the outer surface of the piezoelectric transformer, it is not necessary to route high voltage on the power supply board by the voltage dividing resistor or wiring, and it is possible to prevent dielectric breakdown due to the high voltage applied to the voltage dividing resistor. This makes it easy to reduce the size of the power supply device and improve safety.

According to a sixth aspect of the present invention, in a power supply device using a piezoelectric transformer, a voltage dividing capacitor for dividing an output voltage is formed on an outer surface of the piezoelectric transformer, and a voltage divided by the voltage dividing capacitor is taken out. An output monitoring terminal is provided. According to the above configuration,
Since the voltage divided by the voltage dividing capacitor formed on the outer surface of the piezoelectric transformer can be taken out from the output monitoring terminal, the output voltage can be monitored without providing a voltage dividing resistor or the like for monitoring the output outside the piezoelectric transformer. The size of the power supply device can be reduced, and the exposure of the high voltage portion of the piezoelectric transformer to the outside can be minimized to improve safety.

According to a seventh aspect of the present invention, in an information processing apparatus using a power supply device using a piezoelectric transformer, an output monitoring electrode is formed on an output element of the piezoelectric transformer, and the electrode has a proportional relationship with an output voltage. Wherein an output monitoring terminal for extracting a voltage lower than the output voltage is provided. By providing an output monitoring terminal for taking out a voltage lower than the output voltage, which is proportional to the output voltage in the piezoelectric transformer as described above, the output voltage can be reduced without providing a voltage dividing resistor for output monitoring outside the piezoelectric transformer. Monitoring can be performed, and the size of the power supply device and the size of the information processing device can be reduced.

According to an eighth aspect of the present invention, in an information processing apparatus using a power supply device using a piezoelectric transformer, a voltage dividing resistor for dividing an output voltage is formed on an outer surface of the piezoelectric transformer, and the voltage dividing resistor is formed. An output monitoring terminal for extracting a voltage divided by the above is provided. According to the above configuration, the voltage divided by the voltage dividing resistor formed on the outer surface of the piezoelectric transformer can be taken out from the output monitoring terminal, so that a voltage dividing resistor for output monitoring is not provided outside the piezoelectric transformer. The output voltage can be monitored, and the size of the power supply device and the size of the information processing device can be reduced.

According to a ninth aspect of the present invention, in an information processing apparatus using a power supply device using a piezoelectric transformer, a voltage dividing capacitor for dividing an output voltage is formed on an outer surface of the piezoelectric transformer, and the voltage dividing capacitor is formed by the voltage dividing capacitor. An output monitoring terminal for extracting a divided voltage is provided. According to the above configuration, the voltage divided by the voltage dividing capacitor formed on the outer surface of the piezoelectric transformer can be taken out from the output monitoring terminal. Therefore, a voltage dividing resistor or the like for output monitoring is provided outside the piezoelectric transformer. The output voltage can be monitored without the need, and the power supply device and the information processing device can be reduced in size.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows a basic configuration of a power supply device using a piezoelectric transformer 21 according to a first embodiment of the present invention. The piezoelectric transformer 21 includes an input terminal 21
a, 21b output terminal 21c and output monitoring terminal 21d, for example, 30V, 50k between input terminals 21a, 21b
An AC power supply 22 of about Hz to 100 kHz is supplied, and an AC output voltage generated between the output terminal 21c and the ground line GND is supplied to a load 23 such as a cold cathode tube.

The piezoelectric transformer 21 includes, for example, an input element 25 and an output element 26. The upper and lower surfaces of the input element 25 are provided with electrodes serving as input terminals 21a and 21b. Electrodes are provided. As shown in FIG. 2, the piezoelectric transformer 21 has a band-shaped output monitoring electrode 27 formed on the upper surface of the output element 26 at a distance La from the output terminal 21c.
Is provided with an output monitoring terminal 21d.

In FIG. 2, curve A shows the displacement of each part when a voltage is applied to the piezoelectric transformer 21. Overall length of piezoelectric transformer 21 (length in the longitudinal direction)
Is L, the start end, the end and the center (L / 2
Is the maximum, and the displacement at the position of L / 4 from both ends is zero.

In the piezoelectric transformer 21 having the output monitoring terminal 21d as described above, the voltage V generated at the output monitoring terminal 21d and the distance La from the output terminal 21c to the output monitoring terminal 21d are expressed by the following formula. Have a relationship.

V = Vout × cos (La / L) where V: output voltage of output monitoring terminal 21d Vout: output voltage of output terminal 21c La: distance from output terminal 21c to output monitoring terminal 21d L: piezoelectric transformer 21 If the output monitoring terminal 21d of the piezoelectric transformer 21 is provided in a range of L / 4 from the output terminal 21c, a signal having the same phase as the voltage output from the output terminal 21c can be obtained at the output monitoring terminal 21d. . The output monitoring terminal 21d is connected to the output terminal 21c.
From L / 4 to L / 2, the output terminal 21c
Output monitor terminal 21d
Is obtained.

By providing the output monitoring terminal 21d in the piezoelectric transformer 21 as described above, the voltage from the output monitoring terminal 21d is sufficiently lower than the output voltage of the output terminal 21c, that is, it is in a proportional relationship with the output voltage. In addition, a voltage lower than the output voltage can be taken out as a monitoring voltage. Therefore, the output voltage of the piezoelectric transformer 21 can be monitored without providing a conventionally used voltage dividing resistor for detecting the output voltage, and the size can be reduced.

Next, a specific configuration example of a power supply device using the piezoelectric transformer 21 will be described with reference to FIG. In FIG. 3, reference numeral 30 denotes a DC power supply of, for example, about 5 V, which is supplied to a primary winding of a power transformer 31 via a switching element 32 such as an FET. The switching element 32 is turned on / off by an output control unit 36, which will be described in detail later. The switching element 32 converts a DC voltage supplied from the DC power supply 30 into an AC voltage and supplies the AC voltage to the power transformer 31. The power transformer 31 boosts a supply voltage of, for example, 5 V to a voltage of 30 V, and supplies the voltage to the input terminals 21 a and 21 b of the piezoelectric transformer 21. In this case, one input terminal 21b is connected to the ground line GND. And
An AC output voltage generated between the output terminal 1c of the piezoelectric transformer 21 and the ground line GND is supplied to the load 23.
In this case, the load 23 is provided with a current detector 33 in series. The current detector 33 detects a current flowing through the load 23, and inputs a detection signal to the output control unit 36.

The monitoring voltage output from the output monitoring terminal 21d of the piezoelectric transformer 21 is rectified by the rectifying element 34 and supplied to the overvoltage detecting unit 35. The overvoltage detection unit 35 includes an integrator, integrates the pulsating voltage rectified by the rectifying element 34, compares it with a reference voltage,
When the monitored voltage exceeds the reference voltage, an overvoltage detection signal is output to the output control unit.

The output control section 36 includes, for example, a V / F converter, and turns on / off the switching element 32 at a frequency corresponding to the load current detected by the current detector 33. The piezoelectric transformer 21 is driven at a higher frequency. Output control unit 3
6, when the load current detected by the current detector 33 is lower than the target value, the drive frequency of the piezoelectric transformer 21 is reduced so that the output voltage is increased. When the load current is higher than the target value, the output voltage is reduced. The piezoelectric transformer 21
Is increased so that the load current is maintained at the target value. When an overvoltage is detected by the overvoltage detection unit 35, the output control unit 36 turns off the switching element 32 and stops the voltage supplied from the piezoelectric transformer 21 to the load 23.

As described above, the output control unit 36 controls the drive frequency of the piezoelectric transformer 21 in accordance with the load current detected by the current detector 33, and operates so that the load current is always maintained at the target value. . When an overvoltage is detected by the overvoltage detection unit 35, the output control unit 36 turns off the switching element 32, stops the voltage supplied from the piezoelectric transformer 21 to the load 23, and protects the circuit.

According to the first embodiment, the piezoelectric transformer 21 is provided with the output monitoring terminal 21d.
Since a voltage sufficiently lower than the output voltage of the output terminal 21c from 1d is taken out as a monitor voltage,
The output voltage of the piezoelectric transformer 21 can be monitored without providing a voltage dividing resistor for detecting the output voltage, and the power supply device can be downsized. Further, since there is no need to provide a voltage dividing resistor for detecting the output voltage, exposure of the high voltage portion of the piezoelectric transformer 21 to the outside can be minimized, and safety can be improved. Further, by using the power supply device as a power supply of the information processing device, the size of the power supply device and the information processing device can be reduced.

In the above embodiment, the output control unit 36
In the above, the drive frequency of the piezoelectric transformer 21 is controlled in accordance with the load current detected by the current detector 33 so that the load current is always kept at the target value. In addition, for example, the current detector 33 is omitted. The overvoltage detector 35 detects the normal voltage fluctuation and overvoltage of the piezoelectric transformer 21 and controls the driving frequency of the piezoelectric transformer 21 so that the output voltage of the piezoelectric transformer 21 is maintained at a target value by the voltage fluctuation detection signal. In addition, the switching element 32 may be turned off by an overvoltage detection signal to protect the circuit.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 shows a basic configuration of a power supply device using a piezoelectric transformer according to a second embodiment of the present invention. In the second embodiment,
The voltage dividing resistors 41 and 42 connected in series are formed on the outer surface of the output element 26 of the piezoelectric transformer 21 by using a technique such as thin film printing, and the output monitoring terminal 2 is connected to the connection point of the voltage dividing resistors 41 and 42.
1d. In this case, the voltage dividing resistors 41, 4
2 is formed on one surface of the output element 26 via an insulating film,
One end of the voltage dividing resistor 41 is electrically connected to the output terminal 21c, and one end of the voltage dividing resistor 42 is electrically connected to the input terminal 21a. That is, the voltage dividing resistors 41 and 42 are connected in series between the input terminal 21a and the output terminal 21c of the piezoelectric transformer 21, and the output monitoring terminal 21
d is provided. The values of the voltage dividing resistors 41 and 42 are, for example, several MΩ for the resistor 41 and several tens of kΩ for the resistor 42, and the resistance ratio is set to about several 100: 1.

The piezoelectric transformer 21 configured as described above
The AC power supply 22 is supplied to the input terminals 21a and 21b, and the voltage output from the output terminal 21c is supplied to the load 23. Then, the output control is performed based on the monitoring voltage output from the output monitoring terminal 21d. More specifically, the monitoring voltage output from the output monitoring terminal 21d is supplied via the rectifying element 34 as shown in FIG. Over voltage detector 3
5 is input. The output control for the piezoelectric transformer 21 is the same as in the first embodiment, and a detailed description thereof will be omitted.

As described above, in the second embodiment, the voltage dividing resistors 41, 4 are applied to the piezoelectric transformer 21 by using a technique such as thin film printing.
2 and an output monitoring terminal 21d is provided at the midpoint thereof, and a voltage sufficiently lower than the output voltage of the output terminal 21c is taken out from the output monitoring terminal 21d as a monitoring voltage. The output voltage can be monitored without providing a voltage-dividing resistor for detecting the output voltage outside the device 21, and the size can be reduced. In addition, since the voltage dividing resistors 41 and 42 are integrally provided on the outer surface of the piezoelectric transformer 21, it is not necessary to route a high voltage to the power supply substrate by the voltage dividing resistors and wiring, and the high voltage applied to the voltage dividing resistors is eliminated. This makes it easy to take measures against dielectric breakdown, which makes it possible to reduce the size of the power supply device and improve safety.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5 shows a basic configuration of a power supply device using a piezoelectric transformer according to a third embodiment of the present invention. In the third embodiment,
The voltage dividing capacitors 43 and 44 connected in series on the outer surface of the output element 26 of the piezoelectric transformer 21 using thin film printing or the like.
And an output monitoring terminal 21d is provided at a connection point between the voltage dividing capacitors 43 and 44. In this case, the voltage dividing capacitors 43 and 44 are formed on one surface of the output element 26 via an insulating film, one end of the voltage dividing capacitor 43 is electrically connected to the output terminal 21c, and one end of the voltage dividing capacitor 44 is connected to the output terminal 21c. It is electrically connected to the input terminal 21a. That is, the voltage dividing capacitors 43 and 44 are connected in series between the input terminal 21a and the output terminal 21c of the piezoelectric transformer 21 and have an output monitoring terminal 21d at the middle point.
Is provided. The capacity of the voltage dividing capacitor 43 is made large and the capacity of the voltage dividing capacitor 44 is made small, and the impedance ratio is set to, for example, about several hundred to one.

The piezoelectric transformer 21 configured as described above
Specifically, as shown in FIG.
The monitoring voltage output from 1d is input to the overvoltage detection unit 35 via the rectifier 34. The output control for the piezoelectric transformer 21 is the same as in the first embodiment, and a detailed description thereof will be omitted.

As described above, in the third embodiment, the voltage dividing capacitors 43 and 44 are formed on the piezoelectric transformer 21 by using a technique such as thin-film printing, and an output monitoring terminal 21d is provided at the middle point thereof. Output terminal 2 from terminal 21d
Since a voltage sufficiently lower than the output voltage 1c is taken out as a monitoring voltage, the output voltage can be monitored without providing a voltage-dividing resistor for detecting the output voltage outside the piezoelectric transformer 21, and the size can be reduced. Can be planned. Further, since there is no need to provide a voltage dividing resistor or capacitor outside the piezoelectric transformer 21, exposure of the piezoelectric transformer 21 to the high-voltage portion to the outside can be minimized, and safety can be improved. Can be.

[0037]

As described above, according to the present invention, in a power supply device using a piezoelectric transformer, an output monitoring electrode is formed on an output element of the piezoelectric transformer, and an output monitoring terminal is provided on this electrode. Since a voltage sufficiently lower than that of the load-supply piezoelectric is taken out from this output monitoring terminal as a monitoring voltage, the output voltage of the piezoelectric transformer can be monitored without providing a voltage-dividing resistor for detecting the output voltage. Can be achieved. Further, since there is no need to provide a voltage dividing resistor for detecting the output voltage, exposure of the high voltage portion of the piezoelectric transformer to the outside can be minimized, and safety can be improved.

Further, according to the present invention, a voltage dividing resistor is formed on the outer surface of the piezoelectric transformer by using a technique such as thin film printing.
An output monitoring terminal for taking out the divided voltage is provided, and a voltage sufficiently lower than the load supply voltage is taken out as a monitoring voltage from this output monitoring terminal. The output voltage can be monitored without providing a resistor, miniaturization can be achieved, and high safety can be obtained.

Further, according to the present invention, a voltage dividing capacitor is formed on the outer surface of the piezoelectric transformer by using a technique such as thin film printing, and an output monitoring terminal for extracting a divided voltage is provided. Since a voltage that is sufficiently lower than the voltage is taken out as the monitoring voltage, the output voltage can be monitored without providing a voltage dividing resistor or capacitor outside the piezoelectric transformer, and miniaturization and improvement in safety are achieved. Can be. Further, by using the power supply device using the piezoelectric transformer as a power supply of the information processing device, the size of the power supply device and the information processing device can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a power supply device using a piezoelectric transformer according to a first embodiment of the present invention.

FIG. 2 is a view for explaining an installation position of an output monitoring terminal in the embodiment.

FIG. 3 is a diagram showing a specific example of a circuit configuration according to the embodiment;

FIG. 4 is a diagram showing a basic configuration of a power supply device using a piezoelectric transformer according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a basic configuration of a power supply device using a piezoelectric transformer according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a basic configuration of a power supply device using a conventional piezoelectric transformer.

FIG. 7 is a diagram showing a driving frequency-boosting ratio characteristic of a piezoelectric transformer.

FIG. 8 is a diagram showing a driving frequency-boosting ratio characteristic of a piezoelectric transformer in consideration of load impedance.

FIG. 9 is a diagram showing a specific circuit configuration example of a power supply device using a conventional piezoelectric transformer.

[Explanation of symbols]

 Reference Signs List 21 piezoelectric transformer 21a, 21b input terminal 21c output terminal 21d output monitoring terminal 22 AC power supply 23 load 25 input element 26 output element 27 output monitoring electrode 31 power transformer 32 switching element 33 current detector 34 rectifier 35 overvoltage detector 36 output Control unit 41, 42 Voltage dividing resistor 43, 44 Voltage dividing capacitor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H007 AA12 CB07 CC32 DC05 FA01 FA14 GA08 5H730 AA12 AA20 BB23 EE48 FD01 ZZ19

Claims (15)

[Claims] In a power supply device using a piezoelectric transformer, an output monitoring electrode is formed on an output element of the piezoelectric transformer, and an output for extracting a voltage lower than the output voltage, which is proportional to the output voltage, is formed on the electrode. A power supply device using a piezoelectric transformer, comprising a monitoring terminal. 2. A power supply device using a piezoelectric transformer, wherein an output monitoring electrode is formed on an output element, and the electrode has an output monitoring terminal for taking out a voltage lower than the output voltage, which is proportional to the output voltage. A piezoelectric transformer, and a monitoring voltage output from the output monitoring terminal and a set value are compared, and an overvoltage detection unit that outputs an overvoltage detection signal when the monitoring voltage exceeds a set value; and A power supply device using a piezoelectric transformer, comprising: output stopping means for stopping the output of the piezoelectric transformer in response to the output overvoltage detection signal. 3. A power supply device using a piezoelectric transformer, wherein an output monitoring electrode is formed on an output element, and the electrode has an output monitoring terminal for taking out a voltage which is proportional to the output voltage and lower than the output voltage. A piezoelectric transformer, and output control means for controlling a driving frequency of the piezoelectric transformer in accordance with a monitoring voltage output from the output monitoring terminal, and holding an output of the piezoelectric transformer constant. Power supply device using piezoelectric transformer. 4. A power supply device using a piezoelectric transformer, wherein an output monitoring electrode is formed on an output element, and the electrode has an output monitoring terminal for taking out a voltage lower than the output voltage, which is proportional to the output voltage. A piezoelectric transformer, an output control means for controlling a driving frequency of the piezoelectric transformer in accordance with a monitoring voltage output from the output monitoring terminal or a load current of the piezoelectric transformer, and keeping an output of the piezoelectric transformer constant, An overvoltage detection unit that compares a monitoring voltage output from an output monitoring terminal with a set value and outputs an overvoltage detection signal when the monitoring voltage exceeds a set value; and an overvoltage detection signal output from the overvoltage detection unit. And an output stopping means for stopping the output of the piezoelectric transformer. 5. A power supply device using a piezoelectric transformer, wherein a voltage dividing resistor for dividing an output voltage is formed on an outer surface of the piezoelectric transformer, and an output monitoring terminal for extracting a voltage divided by the voltage dividing resistor is provided. A power supply device using a piezoelectric transformer, which is provided. 6. A power supply device using a piezoelectric transformer, wherein a voltage dividing resistor for dividing an output voltage is formed on an outer surface and an output monitoring terminal for extracting a voltage divided by the voltage dividing resistor is provided. A transformer, a monitoring voltage output from the output monitoring terminal and a set value are compared, and an overvoltage detection unit that outputs an overvoltage detection signal when the monitoring voltage exceeds a set value; And an output stop means for stopping the output of the piezoelectric transformer in response to an overvoltage detection signal. 7. A power supply device using a piezoelectric transformer, wherein a voltage-dividing resistor for dividing an output voltage is formed on an outer surface, and an output monitoring terminal for extracting a voltage divided by the voltage-dividing resistor is provided. A piezoelectric transformer, comprising: a transformer; and an output control unit that controls a driving frequency of the piezoelectric transformer according to a monitoring voltage output from the output monitoring terminal and keeps an output of the piezoelectric transformer constant. Power supply device. 8. A power supply device using a piezoelectric transformer, wherein a voltage-dividing resistor for dividing an output voltage is formed on an outer surface, and an output monitoring terminal for extracting a voltage divided by the voltage-dividing resistor is provided. A transformer; an output control means for controlling a driving frequency of the piezoelectric transformer in accordance with a monitoring voltage output from the output monitoring terminal or a load current of the piezoelectric transformer, and maintaining a constant output of the piezoelectric transformer; Comparing a monitoring voltage output from a terminal with a set value, outputting an overvoltage detection signal when the monitoring voltage exceeds a set value, and an overvoltage detection signal output from the overvoltage detection means. A power supply device using a piezoelectric transformer, comprising: output stopping means for stopping the output of the piezoelectric transformer. 9. A power supply device using a piezoelectric transformer, wherein a voltage dividing capacitor for dividing an output voltage is formed on an outer surface of the piezoelectric transformer, and an output monitoring terminal for extracting a voltage divided by the voltage dividing capacitor is provided. A power supply device using a piezoelectric transformer, which is provided. 10. A power supply device using a piezoelectric transformer, wherein a voltage dividing capacitor for dividing an output voltage is formed on an outer surface and an output monitoring terminal for extracting a voltage divided by the voltage dividing capacitor is provided. A transformer, a monitoring voltage output from the output monitoring terminal and a set value are compared, and an overvoltage detection unit that outputs an overvoltage detection signal when the monitoring voltage exceeds a set value; And an output stop means for stopping the output of the piezoelectric transformer in response to an overvoltage detection signal. 11. A power supply device using a piezoelectric transformer, wherein a voltage dividing capacitor for dividing an output voltage is formed on an outer surface, and an output monitoring terminal for extracting a voltage divided by the voltage dividing capacitor is provided. A piezoelectric transformer, comprising: a transformer; and an output control unit that controls a driving frequency of the piezoelectric transformer according to a monitoring voltage output from the output monitoring terminal and keeps an output of the piezoelectric transformer constant. Power supply device. 12. A power supply device using a piezoelectric transformer, wherein a voltage dividing capacitor for dividing an output voltage is formed on an outer surface, and an output monitoring terminal for extracting a voltage divided by the voltage dividing capacitor is provided. A transformer; an output control means for controlling a driving frequency of the piezoelectric transformer in accordance with a monitoring voltage output from the output monitoring terminal or a load current of the piezoelectric transformer, and maintaining a constant output of the piezoelectric transformer; Comparing a monitoring voltage output from a terminal with a set value, outputting an overvoltage detection signal when the monitoring voltage exceeds a set value, and an overvoltage detection signal output from the overvoltage detection means. A power supply device using a piezoelectric transformer, comprising: output stopping means for stopping the output of the piezoelectric transformer. 13. An information processing apparatus using a power supply device using a piezoelectric transformer, wherein an output monitoring electrode is formed on an output element of the piezoelectric transformer, and the electrode has a proportional relationship with an output voltage. An information processing device comprising an output monitoring terminal for extracting a voltage lower than an output voltage. 14. An information processing apparatus using a power supply device using a piezoelectric transformer, wherein a voltage dividing resistor for dividing an output voltage is formed on an outer surface of the piezoelectric transformer,
An information processing apparatus having an output monitoring terminal for extracting a voltage divided by the voltage dividing resistor. 15. An information processing device using a power supply device using a piezoelectric transformer, wherein a voltage dividing capacitor for dividing an output voltage is formed on an outer surface of the piezoelectric transformer, and the voltage is divided by the voltage dividing capacitor. An information processing apparatus, comprising: an output monitoring terminal for extracting a voltage.