JPH11281693A - Tool for measuring characteristic of piezoelectric transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tool for stably and accurately measuring the characteristics of a piezoelectric transformer by pressing a pair of input electrodes at a position with less vibration by using a conductive contact pin with elasticity, and pressing a buffer material with elasticity where a conductive film has been formed on an output electrode. SOLUTION: With a scondary Rosen type piezoelectric transformer 10, input electrodes 2 and 3 are pressed by conductive contact pins 11 and 12 at the position of 1/4 the length in the longitudinal direction of a piezoelectric ceramic plate 1. Further, the piezoelectric ceramic plate 1 is preferably pressed by contact pins 13 and 14 at the position of 3/4 the length. An output electrode 4 is placed on a conductive film 18, and a pressure for deflecting it slightly is applied to a buffer material 17. The output of a lead wire 23 being connected to the conductive film 18 is measured to obtain the characteristics of the piezoelectric transformer 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig for measuring characteristics of a piezoelectric transformer used in an AC voltage generator such as a backlight of a liquid crystal display.

[0002]

2. Description of the Related Art The structure and operation principle of a conventional piezoelectric transformer will be described below.

Various types of piezoelectric transformers have been devised depending on the structure, arrangement of electrodes, and differences in electrode shape. From the standpoint of manufacturing or boosting ratio, a piezoelectric transformer having the configuration shown in FIG. 1 is practically advantageous. is there.

FIG. 1 is a diagram showing an example of the configuration of a piezoelectric transformer. In FIG. 1, a piezoelectric transformer 10 has a plate-shaped piezoelectric ceramic plate 1, input electrodes 2 and 3 formed on the front and back surfaces of the piezoelectric ceramic plate 1, and positions separated from the input electrodes 2 and 3. And an output electrode 4 formed on one end surface of the piezoelectric ceramic plate 1. In FIG. 1, P indicates the polarization direction. In the piezoelectric transformer 10, the input electrodes 2, 3 arranged in the thickness direction of the piezoelectric ceramic plate 1 are provided.
The electrode part composed of is called a drive part, and the other part is called a power generation part. These drive units and power generation units correspond to the primary and secondary sides of the winding transformer, respectively.

[0005] An input voltage (AC voltage) V1 having a frequency equal to the natural resonance frequency of the piezoelectric transformer 10 is applied to the input electrodes 2 and 3 constituting the drive section in accordance with the length of the piezoelectric ceramic plate 1 in the longitudinal direction. In this case, mechanical vibration is generated along the longitudinal direction of the piezoelectric ceramic plate 1, and a high AC output voltage V <b> 2 is obtained at the output electrode 4 by the mechanical vibration. That is, the piezoelectric transformer 10 is an electric energy-mechanical energy-electric energy conversion element and has a boosting effect. The step-up ratio when the output electrode 4 is not loaded is determined by the piezoelectric material constant of the piezoelectric material constituting the piezoelectric ceramic plate 1 and the dimensions of the piezoelectric ceramic plate 1.

Incidentally, the piezoelectric transformer 10 exhibits a boosting characteristic at the basic resonance frequencies fr, 2fr and 3fr. FIG. 2 is a diagram illustrating a vibration mode at a frequency (2fr) twice the fundamental resonance frequency of the piezoelectric transformer configured as shown in FIG. In FIG. 2, the displacement 5 of the piezoelectric transformer 10 along the longitudinal direction due to the vibration of the piezoelectric ceramic plate 1 is a result measured by a displacement meter or the like using a laser, and the maximum displacement value is 1 μm to 2 μm.
m. As can be seen from FIG. 2, the displacement 5 is maximum at the positions of both ends and the center of the piezoelectric ceramic plate 1, and at a position of の of the length in the longitudinal direction of the piezoelectric ceramic plate 1. It is minimum at the 3/4 position.

Here, 2 having a displacement as shown in FIG.
Next, a method for measuring the characteristics of the Rosen-type piezoelectric transformer will be described. FIG. 3 is a view for explaining a conventional characteristic measuring method for measuring characteristics of the piezoelectric transformer configured as shown in FIG. As shown in FIG. 3, the input electrodes 2, 3 and the output electrode 4 have solders 8a, 8b, 9 respectively.
, The input voltage V1 can be applied to the input electrodes 2 and 3, and the output voltage V2 at the output electrode 4 can be obtained. The vibration of the piezoelectric ceramic plate 1 of the piezoelectric transformer 10 is prevented as much as possible by placing the piezoelectric transformer 10 on a cushioning material 6 such as a sponge provided on a substrate 7 such as a universal substrate. Of the input electrode 2,
3, the output voltage V2 obtained at the output electrode 4 becomes maximum. Therefore, up to now, such a measuring method has been frequently used as a standard measuring method for the characteristics of the piezoelectric transformer.

[0008]

However, in the method of measuring the characteristics of the piezoelectric transformer as described above, it is necessary to fix the lead wires to the input electrodes 2 and 3 constituting the driving section by soldering. The lead wires connected to the input electrodes 2 and 3 must be soldered to a portion of the piezoelectric ceramic plate 1 where the vibration is small so as not to hinder the vibration of the piezoelectric ceramic plate 1 as much as possible. The lead wire connected to the output electrode 4 is soldered to a portion where the vibration of the piezoelectric ceramic plate 1 is maximized.
It is preferable that the amount of solder to be soldered to that portion is as small as possible because the inhibition of vibration of the piezoelectric ceramic plate 1 is small.

In consideration of the above, the input electrodes 2, 3
In the case where lead wires are connected to the output electrode 4 and the output electrodes 4, respectively, there is considerable inconvenience because soldering for that purpose must be performed carefully. In addition, since there is an individual difference in a method of soldering and it varies from person to person, when the characteristics of the piezoelectric transformer are measured after the lead wires are soldered to the input electrodes 2 and 3 and the output electrode 4, the obtained measurement is obtained. The values vary, and accurate characteristics of the piezoelectric transformer cannot be obtained.

There is also a method of measuring the characteristics of the piezoelectric transformer by merely pressing down the piezoelectric ceramic plate 1 using a probe or the like without soldering. In this case, the input electrode 2,
3 can be firmly held at a position where the piezoelectric ceramic plate 1 is less vibrated, but the output electrode 4 is also held down. For this reason, the vibration of the piezoelectric ceramic plate 1 is hindered, and the characteristics of the piezoelectric transformer are reduced, so that accurate characteristics cannot be obtained. In addition, when the vibration of the piezoelectric ceramic plate 1 is large, there is a possibility that the solder may be broken at the solder portion, so that the characteristics of the piezoelectric transformer cannot be measured.

The present invention has been made in view of the above circumstances, and an object of the present invention is to use a pair of input terminals at a position where vibration in the piezoelectric transformer is small and displacement is minimized by using an elastic conductive contact pin. By holding down the electrodes and pressing an elastic cushioning material with a conductive film formed on the output electrodes, the characteristics of the piezoelectric transformer are prevented from deteriorating without hindering the vibration of the piezoelectric transformer as much as possible. An object of the present invention is to provide a piezoelectric transformer characteristic measuring jig capable of stably and accurately measuring a measurement value with less variation.

[0012]

According to a first aspect of the present invention, a pair of input electrodes are formed on the front and back surfaces of a piezoelectric ceramic plate so as to face each other with the piezoelectric ceramic plate interposed therebetween. In a jig for measuring characteristics of a piezoelectric transformer, wherein an output electrode is formed on one end surface of the piezoelectric ceramic plate, an elastic conductive holding member which electrically contacts the pair of input electrodes and holds the piezoelectric transformer. And a deriving means having elasticity for deriving an output from the output electrode by contacting the output electrode.

According to another aspect of the present invention, a pair of input electrodes are formed on the front and back surfaces of a piezoelectric ceramic plate so as to face each other with the piezoelectric ceramic plate interposed therebetween. A piezoelectric transformer characteristic measuring jig in which an output electrode is formed on one end surface of the plate; an elastic conductive holder that electrically contacts the pair of input electrodes to hold the piezoelectric transformer; A resilient support for holding the piezoelectric transformer by contacting a portion of the piezoelectric ceramic plate where the input electrode is not formed; and a resilient derivation for contacting the output electrode and deriving an output from the output electrode. Means.

According to a third aspect of the present invention, there is provided a piezoelectric transformer characteristic measuring jig according to the first or second aspect, wherein the lead-out means includes a conductive film electrically contacting the output electrode. It is characterized by having.

According to the third aspect of the present invention, in the piezoelectric transformer characteristic measuring jig, the conductive film may be made of any one of aluminum, copper, silver, gold, and platinum. It is characterized by becoming.

In the piezoelectric transformer characteristic measuring jig according to the first or second aspect of the present invention, in the fifth aspect of the present invention, the conductive holding member may minimize displacement due to vibration of the piezoelectric ceramic plate. And contacting the input electrode at a certain position.

In the jig for measuring the characteristic of the piezoelectric transformer according to the first or second aspect of the present invention, the holding member may be located at a position where displacement by vibration of the piezoelectric ceramic plate is minimized. The contact is characterized by

[0018]

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

FIG. 4 is a diagram showing a configuration of a jig for measuring characteristics of a piezoelectric transformer according to an embodiment of the present invention. In FIG.
The jig for measuring characteristics of the piezoelectric transformer according to the embodiment of the present invention includes:
The input electrodes 2 and 3 of the secondary Rosen-type piezoelectric transformer 10 having a displacement distribution as shown in FIG. 2 are held down by a predetermined pressure to hold the piezoelectric transformer 10, and an input voltage V1 is applied to the input electrodes 2 and 3. Contact pins 11 and 12 having elasticity (spring property) for making electrical contact with each other, and an input voltage V
(Not shown) and the conductive contact pins 11, 1
Lead wires 21 and 22 for electrically connecting
Supports 15 and 16 for supporting the conductive contact pins 11 and 12 at predetermined positions of the piezoelectric transformer 10, an elastic cushioning material 17 such as a sponge for holding the piezoelectric transformer 10 at a predetermined pressure, and a buffer Base 1 on which material 17 is placed
9 and a conductive film 18 such as a thin conductive foil, which is provided on the buffer material 17 and is in electrical contact with the output electrode 4.
And a lead wire 23 electrically connected to the conductive film 18 for leading the output of the output electrode 4 to the outside.

The jig for measuring the characteristics of the piezoelectric transformer according to the embodiment of the present invention preferably further includes a piezoelectric transformer 1.
The contact pins 13 and 14 having elasticity (spring property) for holding the piezoelectric transformer 10 by pressing the portions where the zero input electrodes 2 and 3 are not formed with a predetermined pressure, respectively. , 14 are also supported by supports 15, 16.

As described above, in the piezoelectric transformer 10, the length of the piezoelectric ceramic plate 1 in the longitudinal direction is 1/1/2.
At the positions 4 and 3/4, the vibration is small and the displacement is minimized.

Therefore, the vibration of the piezoelectric ceramic plate 1 is small using the conductive contact pins 11 and 12, and the predetermined pressure (for example, 100 By holding down the piezoelectric transformer 10 with a pressure of up to 300 g), the piezoelectric transformer 10 itself does not move with the vibration of the piezoelectric ceramic plate 1 and disconnection does not occur.

Preferably, the contact pins 13 and 14 are used to connect the conductive contact pins 11 and 12 at a 1/4 position where vibration of the piezoelectric ceramic plate 1 is small and the input electrodes 2 and 3 are not in electrical contact. Similarly, a predetermined pressure (for example, 100 to 3)
00g), the piezoelectric transformer 10 itself is prevented from moving with the vibration of the piezoelectric ceramic plate 1. The contact pins 13 and 14 are used to minimize the vibration of the piezoelectric ceramic plate 1 and to prevent the piezoelectric transformer 10 from moving due to the vibration. It is desirable to be made of a material having no property.

The conductive film 18 is made of a material hardly oxidized, for example, aluminum (Al), copper (Cu), silver (Ag),
It is made of gold (Au) or platinum (Pt), and has a thickness such that the conductive film 18 itself does not break, for example, 0.0
It has a thickness of from 0.1 mm to 0.1 mm. Note that a conductive liquid material, a conductive tape, or the like can be used instead of the conductive film 18.

When the piezoelectric transformer 10 is mounted vertically with the output electrode 4 side down on the conductive film 18 provided thereon, the cushioning material 17 inhibits the vibration of the piezoelectric ceramic plate 1 as much as possible. The piezoelectric transformer 10 is pressed from the output electrode 4 side so as not to be disconnected and not to be disconnected by the vibration.
Thus, the conductive film 18 and the output electrode 4 of the piezoelectric transformer 10 come into electrical contact.

By providing an elastic body such as a spring below the cushioning member 17 so as to constantly apply a constant pressure to the piezoelectric transformer 10, vibration of the piezoelectric ceramic plate 1 is prevented as much as possible. Disconnection due to the vibration can be prevented.

Next, a method for measuring the characteristics of the piezoelectric transformer using the jig for measuring the characteristics of the piezoelectric transformer according to the embodiment of the present invention will be described.

As a piezoelectric transformer to be measured, a secondary Rosen type piezoelectric transformer 10 having a displacement distribution as shown in FIG. 2 due to the vibration of the piezoelectric ceramic plate 1 is used.

First, before measuring the characteristics of the piezoelectric transformer 10, as shown in FIG. 4, the piezoelectric transformer 10 is vertically fixed by a jig for measuring the characteristics of the piezoelectric transformer. That is, in the piezoelectric transformer 10, the output electrode 4 is arranged so as to be located below the input electrodes 2, 3, and the piezoelectric transformer 10
In the longitudinal direction of the piezoelectric ceramic plate 1 at a position １ ／ of the length thereof so that the piezoelectric ceramic plate 1 does not move due to the vibration of the piezoelectric ceramic plate 1.
The input electrodes 2 and 3 are pressed using the conductive contact pins 11 and 12 at a pressure of about 00 to 300 g.

In the longitudinal direction of the piezoelectric ceramic plate 1, at a position 、 of the length thereof, the conductive contact pins 11,
Similarly to 12, the portions where the input electrodes 2 and 3 are not formed are pressed using the contact pins 13 and 14 at a pressure of about 100 to 300 g.

Further, the cushioning member 17 composed of sponge
The output electrode 4 is placed on the conductive film 18 made of silver foil having a thickness of about 0.001 mm to 0.1 mm provided thereon, and a pressure is applied to the buffer material 17 so that the output electrode 4 slightly bends. The electrode 4 and the conductive film 18 are brought into electrical contact.

As described above, the output derived from the lead wire 23 electrically connected to the conductive film 18 is applied to the piezoelectric transformer 10 fixed to the characteristic measuring jig of the piezoelectric transformer shown in FIG. By measuring, the characteristic value of the piezoelectric transformer 10 is obtained.

FIG. 5 is a diagram showing a configuration of a measuring circuit for measuring the characteristics of the piezoelectric transformer using the jig for measuring the characteristics of the piezoelectric transformer according to the embodiment of the present invention. In FIG. 5, a measurement circuit for measuring the characteristics of the piezoelectric transformer 10 includes a basic resonance frequency fr of the piezoelectric transformer 10 applied to the input electrodes 2 and 3.
A power supply 30 for generating an input voltage V1 having a frequency 2fr twice the frequency of the power supply 30 and an ammeter 31 for measuring an input current I1
, A load resistor RL connected to the output electrode 4, a voltmeter 32 and a resistor 33 for measuring the output current I2, and the input current I1 and the output current I2
Is measured, and the characteristic value of the piezoelectric transformer 10 is obtained based on the measurement result.

FIG. 6 is a diagram showing the characteristic results of the piezoelectric transformer obtained by the conventional method for measuring the characteristics of the piezoelectric transformer as shown in FIG. 3, and as shown in FIG. 5 is connected to the lead wire by soldering.
5 shows characteristic results obtained by measuring an input current I1 and an output current I2 by a measurement circuit as shown in FIG.

Here, the input current I1 and the output current I2 of the four piezoelectric transformer samples are measured by an ammeter 31.
And using a voltmeter 32. The boost ratio is the ratio of the input voltage V1 to the output voltage V2 (V2 / V1)
And the output voltage V2 is obtained by the output current I2 and the load resistance RL. The efficiency (%) is the input power P
1 shows a ratio (P2 / P1) between 1 and output power P2,
The input power P1 is obtained from the input voltage V1 and the input current I1, and the output power P2 is obtained from the output voltage V2 and the output current I1.
2 obtained. Note that the boost ratio and the efficiency shown in FIG. 6 indicate values when the output power is 1 W. FIG.
As shown in the above, the standard deviations of the step-up ratio and the efficiency of the four piezoelectric transformers are 0.284 and 3, respectively.
013.

On the other hand, FIG. 7 is a diagram showing the characteristic results of the piezoelectric transformer using the piezoelectric transformer characteristic measuring jig according to the embodiment of the present invention. As shown in FIG. It is a characteristic result obtained by measuring the input current I1 and the output current I2 with the measurement circuit fixed as shown in FIG.

Here, similarly to the case where the characteristic results shown in FIG. 6 are obtained, the input current I1 and the output current I2 of the four piezoelectric transformer samples are measured using the ammeter 31 and the voltmeter 32, respectively. ing. The boost ratio and efficiency (%) indicate the above-described ratios, respectively, and the boost ratio and efficiency illustrated in FIG. 7 indicate values when the output power is 1 W, similarly to the result illustrated in FIG. As shown in FIG. 7, the standard deviations of the boost ratio and the efficiency of the four piezoelectric transformers are 0.031 and 0.427, respectively.

Therefore, comparing the characteristic results of the piezoelectric transformers shown in FIGS. 6 and 7, there is a difference of one digit or more between the step-up ratio and the standard deviation of the efficiency, and the characteristic measuring jig according to the embodiment of the present invention. Since the value obtained by the characteristic measurement using the method has much less variation between samples than the value obtained by the characteristic measurement by soldering the lead wire, it can be seen that accurate characteristic measurement is performed.

As described above, according to the characteristic measuring jig of the piezoelectric transformer according to the embodiment of the present invention, the vibration of the piezoelectric transformer is not hindered as much as possible, and it does not depend on the individual difference of the measurer. This makes it possible to more accurately and quickly measure the characteristics of the piezoelectric transformer. In the embodiment of the present invention, as described above, since the piezoelectric transformer is fixed vertically, the laser is irradiated from above with a displacement meter using a laser in this state, for example. Displacement due to vibration can be easily measured.

Here, the case where the piezoelectric transformer is fixed vertically is described. However, even when the piezoelectric transformer is fixed horizontally (floating the piezoelectric transformer in the air by supporting it at four points), the piezoelectric transformer is more accurate. And quick characteristic measurement becomes possible. When the piezoelectric transformer is fixed horizontally, the displacement of the piezoelectric transformer due to vibration can be easily measured by irradiating the laser from the lateral direction (horizontal direction) with a displacement meter using a laser in this state. can do.

[0041]

As described above, according to the present invention, a pair of input electrodes are pressed at positions where vibration in the piezoelectric transformer is small and displacement is minimized by using conductive contact pins having elasticity. By pressing the cushioning material having the elasticity formed, the characteristics of the piezoelectric transformer are prevented from deteriorating without hindering the vibration in the piezoelectric transformer as much as possible, and the characteristics of the piezoelectric transformer can be stably reduced by reducing the dispersion of the measured values. It can be measured accurately.
This makes it possible to easily measure the characteristics of the piezoelectric transformer.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a configuration of a piezoelectric transformer.

FIG. 2 is a diagram showing a vibration mode at twice the fundamental resonance frequency of the piezoelectric transformer configured as shown in FIG.

FIG. 3 is a diagram for explaining a conventional characteristic measuring method for measuring characteristics of the piezoelectric transformer configured as shown in FIG.

FIG. 4 is a diagram showing a configuration of a jig for measuring characteristics of a piezoelectric transformer according to an embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a measurement circuit for measuring the characteristics of the piezoelectric transformer using the jig for measuring the characteristics of the piezoelectric transformer according to the embodiment of the present invention.

FIG. 6 is a diagram showing characteristic results of a piezoelectric transformer obtained by a conventional method for measuring characteristics of a piezoelectric transformer as shown in FIG.

FIG. 7 is a diagram illustrating a characteristic result of the piezoelectric transformer obtained by using the jig for measuring the characteristic of the piezoelectric transformer according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric ceramic plate 2, 3 Input electrode 4 Output electrode 10 Piezoelectric transformer 11, 12 Conductive contact pin 13, 14 Contact pin 15, 16 Support 17 Buffer material 18 Conductive film 19 Base 21, 22, 23 Lead wire 30 Power supply 31 ammeter 32 voltmeter 33 resistance

Claims (6)

[Claims] 1. A characteristic measurement of a piezoelectric transformer in which a pair of input electrodes are formed on the front and back surfaces of a piezoelectric ceramic plate with the piezoelectric ceramic plate sandwiched therebetween and an output electrode is formed on one end surface of the piezoelectric ceramic plate. In the jig, a conductive holder having elasticity for electrically contacting the pair of input electrodes and holding the piezoelectric transformer, and elasticity for contacting with the output electrodes to derive an output from the output electrodes. A jig for measuring characteristics of a piezoelectric transformer, comprising: 2. A characteristic measurement of a piezoelectric transformer in which a pair of input electrodes are formed on the front and back surfaces of a piezoelectric ceramic plate with the piezoelectric ceramic plate interposed therebetween and an output electrode is formed on one end surface of the piezoelectric ceramic plate. In the jig, an elastic conductive holder that electrically contacts the pair of input electrodes and holds the piezoelectric transformer, and contacts a portion of the piezoelectric ceramic plate where the input electrodes are not formed. A characteristic measuring jig for a piezoelectric transformer, comprising: a holding member having elasticity for holding the piezoelectric transformer; and a deriving means having elasticity for deriving an output from the output electrode in contact with the output electrode. . 3. The device according to claim 1, wherein the deriving unit has a conductive film that is in electrical contact with the output electrode.
Or the jig for measuring characteristics of the piezoelectric transformer according to 2. 4. The conductive film is made of aluminum, copper,
4. The jig for measuring characteristics of a piezoelectric transformer according to claim 3, wherein the jig is made of any one of silver, gold, and platinum. 5. The piezoelectric transformer according to claim 1, wherein the conductive holder comes into contact with the input electrode at a position where displacement caused by vibration of the piezoelectric ceramic plate is minimized. jig. 6. The jig for measuring the characteristics of a piezoelectric transformer according to claim 1, wherein the holder comes into contact at a position where displacement by vibration of the piezoelectric ceramic plate is minimized.