JPH07177736A - Piezoelectric transformer protection device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a piezoelectric transformer protection device which prevents the piezoelectric transformer from being damaged and prevents the entire circuit from being burnt out when the piezoelectric transformer is damaged. A piezoelectric transformer, a power supply switch for stopping the supply of power to drive the piezoelectric transformer, an output detector for detecting the output of the piezoelectric transformer, a detection value of the output detector, and a predetermined reference. A comparison unit that compares the value and a control unit that controls the power supply switch based on the comparison result are provided. In addition to the above configuration, a display unit that displays the comparison result is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer protection device.

[0002]

2. Description of the Related Art In a piezoelectric transformer, since the load resistance and the input resistance are in inverse proportion to each other, when the load is short-circuited, the input resistance automatically increases. Further, because of its simple structure and small size and light weight, it is used in, for example, continuous ignition devices, televisions, and the like, and its applications are being expanded in various fields.

Hitherto, in the use of such a piezoelectric transformer, no means has been provided for preventing cutting damage during driving of the piezoelectric transformer and burning damage caused by the cutting damage.

[0004]

By the way, when a piezoelectric transformer is excited from its primary side at its resonance frequency, a sine wave voltage boosted by the impedance ratio between the primary side and the secondary side is generated between the secondary side terminals. During this operation, the stress of the piezoelectric transformer is greatly different between when there is a load on the output and when there is no load, and the piezoelectric transformer may be cut off when the load becomes lighter while generating a voltage matching the load.

Further, in the case of such cutting, what is more dangerous is that an arc may be generated at this time. If this arc lasts for a long time, the entire circuit burns out, which is extremely dangerous.

In view of the above points, it is an object of the present invention to provide a piezoelectric transformer protection device capable of preventing damage and preventing the entire circuit from being burned even if the damage occurs. To do.

[0007]

In order to achieve the object of the present invention, description will be given based on FIG. 1 which is a basic conceptual diagram thereof.

First, the piezoelectric transformer protection device of the present invention (hereinafter referred to as invention 1) corresponding to claim 1 is a power supply for stopping the supply of the piezoelectric transformer T and the power supply 5 for driving the piezoelectric transformer T. The supply switch 4, the output detection unit 1 that detects the output of the piezoelectric transformer T, and the comparison unit 2 that compares the detection value of the output detection unit 1 with a predetermined reference value.
And a control unit 3 for controlling the power supply switch 4 based on the comparison result.

In addition to the means of the invention 1 described above, the piezoelectric transformer protection device of the invention of the present application (hereinafter referred to as invention 2) corresponding to claim 2 is a display unit 6 for displaying the comparison result of the comparison unit 2. It is characterized by being equipped with.

[0010]

In the first aspect of the invention, the on / off of the power supply switch 4 is always controlled by the controller 3 by comparing and comparing the output of the piezoelectric transformer T and a predetermined reference value.
Abnormalities in the operation of the piezoelectric transformer T can be detected, and the measures can be taken immediately. Further, by appropriately setting the predetermined reference value, the detection range can be made versatile and the detection can be performed stepwise.

In addition to the operation of the above-mentioned invention 1, in the invention 2, the result of the comparison judgment in the comparison part 2 is displayed on the display part 6, and by observing the display content, for example, what kind of abnormality is Etc. are recognized.

[0012]

FIG. 2 is a circuit block diagram showing the configuration of an embodiment of the present invention. Hereinafter, description will be given with reference to the drawings.

The left half of the piezoelectric transformer T is a drive part, and the right half is a power generation part. Drive electrodes are provided on the upper and lower surfaces of the drive portion and are polarized in the thickness direction. On the other hand, the power generation portion is provided with an output electrode on its right end face and is polarized in the length direction. The drive electrodes are connected to a power supply 5a via a power supply switch 4a that supplies or stops the power supply for driving the piezoelectric transformer T. This power supply switch 4a is
It has a latch function. On the other hand, piezoelectric transformer T
A voltage detection circuit 1a is provided on the output electrode side of, and in this configuration, resistors R ₁ and R ₂ having a predetermined ratio are connected in series, and a voltage follower L ₁ serves as a first stage buffer via a diode. It is connected between the two resistors R ₁ and R ₂ . Further, a comparison circuit 2a for comparing the detected value from the voltage detector 1a with a reference value is provided, and the buffer of the voltage follower L ₁ described above is a voltage
As compared with the amplifier of the comparator L _2, L _3, L ₄ has a configuration in which takes place. The signal of the first stage buffer is
The voltage comparator L ₂ receives the minus signals, the voltage comparator L ₃ receives the plus and minus signals, and the voltage comparator L ₄ receives the plus signals, and the voltage comparators L ₂ , L ₃ and L ₄ receive these comparators. A resistor R ₃ , respectively connected to
The operation is performed by comparison with a reference value set by R ₄ , resistors R ₅ , R ₆ , and resistors R ₇ , R ₈ . That is, if it is within the range of the reference value in each voltage comparator, the voltage comparator operates,
The corresponding light emitting diodes D ₁ , D ₂ and D ₃ are operated. The voltage comparator L
₂ and L ₄ are respectively connected to light emitting diodes D ₁ and D ₃ via data stretching latches L ₅ and L ₆ , respectively.
It is connected to the. This light emitting diode D ₁ , D ₂ , D
The blinking state of the indicator 20 consisting of ₃ allows you to visually confirm the abnormality.

The operation of the embodiment of the present invention having the above configuration will be described by taking the case of an output voltage of 2.0 KV as an example.
Table 1 shows the voltage input to each resistor and each amplifier in this embodiment.

[0015]

[Table 1]

The resistor R ₁ needs to be large enough so as not to affect the output voltage. First, the output voltage of the voltage follower L ₁ is 1.0 V. In addition, the voltage comparator L ₂ is 0.75V or less (output voltage 1.5 k
V or less), the voltage comparator L ₃ is 0.75V
Over 1.00 V (output voltage 1.5 kV ~ 2.0 kV),
The voltage comparator L ₄ operates at 1.00 V or higher (output voltage 2.0 kV or higher). When an abnormality occurs on the primary side of the piezoelectric transformer T, the output voltage decreases and the voltage follower L ₁ operates,
The light emitting diode D ₁ is turned on through the data stretch latch L ₅ , and the power supply switch 4a is turned “OFF” to stop the power supply. On the other hand, when an abnormality occurs on the secondary side of the piezoelectric transformer T, the output voltage rises and the voltage follower L ₄ operates, whereby the light emitting diode D ₃ lights up via the data stretching latch L _6. , Power supply switch 4a
Is turned off and the power supply is stopped. In this way, the protection circuit of the piezoelectric transformer T operates, and it is possible to prevent the piezoelectric transformer T from being cut or burned due to an abnormal load.

When the voltage is normal, the voltage comparator L operates to turn on the light emitting diode D ₂ . In this way, by visually confirming the blinking state of the light emitting diode installed in the indicator 20,
It is possible to recognize an abnormality in the operation of the piezoelectric transformer T.

Next, another embodiment of the present invention will be described. FIG. 3 is a circuit block diagram showing the configuration of the embodiment of the present invention. Hereinafter, description will be given with reference to the drawings. The piezoelectric transformer T used here is the same as that described above, and the description thereof is omitted. The drive electrode of the piezoelectric transformer T has a power supply switch 4a for supplying or stopping the power supply for driving the piezoelectric transformer T.
Is connected to the power source 5a via. The power supply switch 4a has a latch function. on the other hand,
A voltage detection circuit 1a is provided on the output electrode side of the piezoelectric transformer T, and this configuration has resistors R ₁ and R ₂ having a predetermined ratio.
Are connected in series, and the voltage
The follower L ₁ has both resistances R ₁ and R
Connected between _two . The comparison circuit 2a is provided for comparing the detected value from the voltage detector 1a to the reference value, the above-mentioned buffer voltage follower L ₁ is a comparison in each amplifier of the voltage comparator L _2, L ₃ Is performed. The signal from the first-stage buffer is minus by the voltage comparator L ₂ .
The voltage comparator L ₃ receives a plus signal, and the voltage comparators L ₂ and L ₃ have resistors R ₃ and R ₃ respectively connected to these comparators.
The operation is performed by comparison with a reference value set by R ₄ and resistors R ₅ and R ₆ . That is, when the voltage is within the range of the reference value of each voltage comparator, the voltage comparator operates and the corresponding light emitting diodes D ₁ and D ₂ operate. The voltage comparator L ₃ is connected to the light emitting diode D ₂ via the data stretching latch L ₄ . An abnormality can be visually confirmed by the blinking state of the indicator 30 including the light emitting diodes D ₁ and D ₂ .

The operation of the embodiment of the present invention having the above configuration will be described by taking the case where the output voltage is 2.0 KV as an example.
Table 2 shows the voltage input to each resistor and each amplifier in this embodiment.

[0020]

[Table 2]

The resistance R ₁ needs to be large enough not to affect the output voltage. First, the output voltage of the voltage follower L ₁ is 1.0 V. Further, the voltage comparator L ₂ has a function as an'L 'level detection comparator, and when it is less than 1.00 V, it operates to turn on the diode D ₁ . Further, the voltage comparator L ₃ has a function as an “H” level detection comparator, and when the load is abnormal, 1.00
When the voltage exceeds V, the light emitting diode D ₂ lights up via the data stretching latch L ₄ , and the power supply switch 4a is turned “OFF” to stop the power supply. In this way, the protection circuit of the piezoelectric transformer T operates, and it is possible to prevent the piezoelectric transformer T from being cut or burned due to an abnormal load.

Also in this embodiment, similarly to the above-described embodiment, the abnormality in the operation of the piezoelectric transformer T can be recognized by visually confirming the blinking state of the light emitting diode installed in the indicator 30.

In both of the above-described two embodiments, the abnormality of the load of the piezoelectric transformer is recognized by detecting the voltage. As means for detecting this voltage, in addition to the configuration described above, there is a configuration using the V / F converter shown in FIG. 4, the photocoupler shown in FIG. 5, the FET shown in FIG. 6, and the transoma shown in FIG.

The VF converter shown in FIG. 4 is configured to convert the amount of change in voltage into a frequency and obtain a drive signal for the next stage circuit. In this case, the indicator can be displayed at this frequency. A ₁ integrates the input voltage, and A ₂ is inverted according to the output voltage level, so Tr ₁ becomes'O '.
N ',' OFF '.

In the photocoupler shown in FIG. 5, the light emitting diode D ₅₁ is driven by a change in voltage, and the output thereof is received by the phototransistor Tr ₅₁ . Since the FET shown in FIG. 6 has a high input resistance, it can handle a high voltage.

The transformer ohmer shown in FIG. 7 is for detecting that when the input voltage changes, a voltage change occurs on the secondary side of the transformer accordingly. The embodiment of the present invention is not limited to the structure for detecting the voltage as described above as the means for detecting the abnormality of the load, but the structure for detecting the current as shown in FIG. 8 and the structure as shown in FIG. There is a configuration for detecting the frequency.

The configuration of FIG. 8 is basically the same as that of the voltage detecting circuit, but using the input current I and the reference resistor R ₈₁ , A
The product is obtained by ₈₁ and the output voltage is obtained.

Further, the FV converter shown in FIG. 9 generates a DC voltage proportional to the input frequency, and is configured to convert the frequency change into a voltage. This voltage is obtained as the output voltage.

As described above, by detecting an abnormality in the load of the piezoelectric transformer by these means, when there is an abnormality, the power supply switch is turned off and the power supply is stopped. It Therefore, it is possible to prevent the piezoelectric transformer from being cut or burnt.

In the present embodiment, the indicator is constructed by using the light emitting diode, but the present invention is not limited to this, and other alternative means by which the result of the comparison judgment can be recognized by human eyes or ears may be used. For example, the detected output voltage of the piezoelectric transformer may be A / D converted to obtain a digital display value thereof, and the result of the comparison determination may be digitally displayed.

[0031]

As described above, according to the piezoelectric transformer protection device of the first aspect, the piezoelectric transformer, the power supply switch for stopping the supply of the power source for driving the piezoelectric transformer, and the output of the piezoelectric transformer. Since it has a configuration including an output detection unit that detects the, a comparison unit that compares the detection value of the output detection unit with a predetermined reference value, and a control unit that controls the power supply switch based on the comparison result. It is possible to prevent breakage, and even if the breakage occurs, the entire circuit will not be burnt out.

According to the second aspect of the invention, in addition to the effect of the first aspect, it is possible to accurately recognize whether the operation of the piezoelectric transformer is normal or abnormal by observing the contents displayed on the display section.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of the present invention.

FIG. 2 is a circuit block diagram showing a configuration of an embodiment of the present invention.

FIG. 3 is a circuit block diagram showing the configuration of another embodiment of the present invention.

FIG. 4 is a detection circuit diagram applied to an embodiment of the present invention.

FIG. 5 is a detection circuit diagram applied to an embodiment of the present invention.

FIG. 6 is a detection circuit diagram applied to an embodiment of the present invention.

FIG. 7 is a detection circuit diagram applied to an embodiment of the present invention.

FIG. 8 is a detection circuit diagram applied to an embodiment of the present invention.

FIG. 9 is a detection circuit diagram applied to an embodiment of the present invention.

[Explanation of Codes] 1 ... Output detection unit 2 ... Comparison unit 3 ... Control unit 4 ... Power supply switch 5 ... Power supply 6 ... Display unit T. ... Piezoelectric transformers

Claims (2)

[Claims] 1. A piezoelectric transformer, a power supply switch for stopping the supply of power to drive the piezoelectric transformer, and an output detector for detecting the output of the piezoelectric transformer,
A protective device for a piezoelectric transformer, comprising: a comparison unit that compares a detection value of the output detection unit with a predetermined reference value; and a control unit that controls the power supply switch based on the comparison result. 2. A piezoelectric transformer, a power supply switch for stopping the supply of power to drive the piezoelectric transformer, and an output detector for detecting the output of the piezoelectric transformer,
A display for displaying the comparison result, which includes a comparison unit for comparing the detection value of the output detection unit with a predetermined reference value, and a control unit for controlling the power supply switch based on the comparison result. Protective device for piezoelectric transformers.