JP2001196653A - Piezoelectric transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a piezoelectric transformer element from generating noise without degrading conversion efficiency by bringing the element into contact with a case body. SOLUTION: The piezoelectric transformer element 1 is accomodated in the case constituted of an upper case 2a and a lower case 2b, in which an upper load terminal 3a and a lower load terminal 3b are insert molded, respectively. At that time, an elastic adhesive agent 4 is applied at two portions of the upper case 2a and at three portions of the lower case 2b. The piezoelectric transformer element is accomodated inside the case, so that the element 1 is bonded and fixed by the elastic adhesive agent 4 to the upper and the lower cases 2a, 2b without directly bringing the element 1 into contact with the inner walls of the upper and the lower cases 2a, 2b. The lead terminals 3a, 3b are brought into contact with the electrodes of the element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter circuit for a cold cathode ray tube backlight of a liquid crystal panel such as a notebook type personal computer and a car navigation system, an adapter power supply circuit generally used for consumer products, and a high voltage generator used for an electronic copying machine. The present invention relates to a piezoelectric transformer used in a circuit or the like, and particularly to a structure for holding a piezoelectric transformer element in a case of the piezoelectric transformer.

[0002]

2. Description of the Related Art FIGS. 12A and 12B are a longitudinal sectional view and a transverse sectional view showing a casing structure of a conventional piezoelectric transformer of this kind. The upper case 12a and the lower case 12b are resin molded products, and three upper lead terminals 13a and three lower lead terminals 13b are insert-molded respectively. A projection 14 is provided on the inner surfaces of the upper case and lower case.
Are formed. Three electrodes 11a are formed on the upper and lower surfaces of the piezoelectric transformer element 11, respectively, and an upper lead terminal 13a or a lower lead terminal 13b is in contact with a vibration node point on each electrode. The element 11 is held in a case. The protrusion 14 formed on the inner surface of the case prevents the piezoelectric transformer 11 from excessively moving from a predetermined holding position.

[0003]

In the above-mentioned conventional example,
Since the upper and lower surfaces of the piezoelectric transformer element are held only by the elastic force of the lead terminals, the piezoelectric transformer element is likely to be displaced when a horizontal shock is applied, and the piezoelectric transformer element is easily attached to the protrusion 14 or the inner wall of the case. Contact. When the piezoelectric transformer element comes into contact with a projection of the case or the like, the vibration characteristics of the transformer element are deteriorated, and vibration of a frequency in an audible sound range is applied to the piezoelectric transformer element, and the vibration propagates to the case and generates noise.

Therefore, the problem to be solved by the present invention is:
An object of the present invention is to provide a piezoelectric transformer that does not cause a displacement of a piezoelectric transformer element even when an impact is applied, without lowering the output.

[0005]

According to the present invention, there is provided a piezoelectric transformer element having electrodes formed on upper and lower surfaces of a long plate-shaped piezoelectric body, and a housing for accommodating the piezoelectric transformer element. An insulating case having an insert-molded lead terminal, wherein the piezoelectric transformer element is pressed from above and below by the lead terminal at its vibration node point, and upper and lower surfaces and side surfaces of the piezoelectric transformer element A piezoelectric transformer is provided, wherein an insulating elastic member is interposed between the vibration node point and the vibration non-node point and the insulating case.

The insulating elastic member provided between the side and upper and lower surfaces of the piezoelectric transformer element and the insulating case is made of an elastic adhesive applied to the upper and lower surfaces of the insulating case. Elastic bonding formed on upper and lower surfaces of the piezoelectric transformer element and elastic projections formed on four side surfaces thereof, which is formed so as to extend to the side surface of the piezoelectric transformer element; and elastic bonding applied on upper and lower surfaces of the insulating case. And an elastic projection formed on four side surfaces of the piezoelectric transformer element.

[0007] Preferably, the insulating elastic member is made of a silicone-based or urethane-based material, and has a hardness of 30 to 80 (according to JIS K6253). Further, the contact area of the insulating elastic member with the piezoelectric transformer element is 0.5 to
It is made to 1.5mm ^2. [Operation] In the conventional example described above, the piezoelectric transformer element is pressed and held by the lead terminal at the node of the vibration. This is because, when a vibrating body such as a piezoelectric transformer element is to be held, the energy conversion efficiency of the piezoelectric transformer element is reduced due to the inhibition of the vibration unless the vibration body is held at a node point of the vibration. However, according to experiments performed by the present inventors, even when auxiliary non-node points are also held, when the piezoelectric transformer element is held by an elastic body, a large decrease in conversion efficiency is caused. It turned out not to be possible. That is, as the formation position of the insulating elastic member, not only the vibration node point, but also at the vibration non-node point, the contact area between the elastic body and the piezoelectric transformer element, the hardness of the elastic body, the position of the non-node point, etc. are appropriately determined. It has been found that by making a selection, it is possible to keep the decrease in efficiency low.

In the present invention, the node point of the piezoelectric transformer element is held by the lead terminal, and the non-node point of the piezoelectric transformer element having a relatively small amplitude is held by an elastic body. It is preferable that the position of the transformer element that comes into contact with the elastic body is at or near a position where a line parallel to the side of the element passing through the node point crosses another side of the element. In the present invention, the hardness is 30 to 80 (JIS K).
However, if the hardness is lower than this, it is difficult to hold the transformer element in a predetermined position, and if the hardness is higher than this, the conversion efficiency of the transformer element is greatly reduced. is there. For the same reason, the contact area between the elastic body and the transformer element is 0.5 to 1.5 mm ² per location (element area is 200 to 300 mm).
² , when the element thickness is 0.5 to 1.5 mm and the contact points are 10 to 12).

By holding the vibration node point and the vibration non-node point on the side surface of the piezoelectric transformer element with an elastic body, the piezoelectric transformer element moves in the horizontal direction due to vibration of the element itself or external force (vibration, impact). Can be prevented. Also, by holding the vibration node points and the vibration non-node points on the upper and lower surfaces (front and back surfaces) of the piezoelectric transformer element with elastic bodies, it is possible to prevent the piezoelectric transformer element from tilting due to vibration of the element itself or external force. it can. Therefore, it is possible to prevent the lead terminal from hindering the vibration of the piezoelectric transformer element and lowering the conversion efficiency due to the shift of the contact point between the piezoelectric transformer element and the terminal lead from the node point, and to prevent the transfer element from contacting the case. Noise can be prevented.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings. [First Embodiment] FIG.
FIG. 1 is an exploded perspective view showing a first embodiment of the present invention, and FIG. 2 is a plan view showing a positional relationship of each part of the first embodiment of the present invention.

1 and 2, a piezoelectric transformer element 1 includes an upper lead terminal 3a and a lower lead terminal 3b.
Are housed in a case 2 composed of an upper case 2a and a lower case 2b, each of which is insert-molded. The upper case 2a has a snap-fit finger 5, and the casing is formed by fitting the snap-fit finger 5 to the lower case 2b. When the piezoelectric transformer element 1 is stored, the upper case 3a has two points ( all node points ) , and the lower case 3b has three points (including one non-node point). The elastic adhesive 4 is applied to a vibration node point at a position where a perpendicular line drawn from the center of each electrode to the long side of the element intersects the inner wall of the case or a vibration non-node point in the vicinity thereof. Then, by housing the element in a case, the elastic adhesive 4
Thus, the piezoelectric transformer element 1 is bonded to the upper case 2a and the lower case 2b, respectively, and the piezoelectric transformer element is bonded and fixed to the case without directly contacting the inner wall surfaces of the cases 2a and 2b. Therefore, the vibration node point and the vibration non-node point of the piezoelectric transformer element are held by the elastic body.

In the present invention, the node point is located on the node region of the piezoelectric transformer element. When a rectangular piezoelectric transformer element as shown in FIG. 1 is caused to vibrate in the third mode, a cross-sectional area (a region surrounded by a dotted line) crossing the center of each electrode 1a and perpendicular to the long side of the transformer element is a node region. . A straight line portion where the surface of the node region N intersects the upper and lower planes and both side surfaces of the piezoelectric transformer element 1 can be called a node line, and any point on this node line is a node point intended by the present invention. In addition, the non-node point in the present invention is, as described above, a region where the piezoelectric transformer element has a relatively small amplitude is a non-node point,
According to the present invention, the piezoelectric transformer element is held by an insulating elastic member at a vibration node point at a position where a perpendicular line drawn from a vibration node point to a long side of the element intersects an inner wall of the insulating case or at a vibration non-node point in the vicinity thereof. There is something intended.

Next, a method of bonding and fixing the piezoelectric transformer element 1 in the present embodiment will be described. FIG. 3 is an enlarged cross-sectional view illustrating a method of bonding and fixing the piezoelectric transformer element according to the present embodiment. First, the elastic adhesive 4 is applied to the lower case 2b. When the piezoelectric transformer element 1 is mounted on the lower case 2b after applying the elastic adhesive 4, the elastic adhesive 4
Can also move around in the thickness direction of the piezoelectric transformer element 1, and the piezoelectric transformer element 1 can be fixed in the lower case 2b while maintaining a certain clearance with respect to the lower case 2b. Next, by mounting the upper case 2a coated with the elastic adhesive 4 on the lower case 2b, the piezoelectric transformer of this embodiment can be obtained.

Since the piezoelectric transformer element 1 is held by the case 2 via the elastic adhesive 4 having elasticity and does not directly contact the case 2, the vibration of the piezoelectric transformer element 1 is not hindered. Also, no noise is generated.

[First Embodiment] Next, a first embodiment of the present invention will be specifically described. First, the shape of the piezoelectric transformer element 1 is length L = 42 mm, width W = 5.5 mm, and thickness t = 1 mm. Zenite 7130 (trade name, manufactured by Dubon), which is a liquid crystal polymer, was used as a molding material for Case 2. The outer dimension of the molding material of the case 2 is a length L = 4 when the upper and lower cases 2a and 2b are combined.
4.4 mm, width W = 7.8 mm, and thickness t = 3.2 mm.

FIGS. 4A and 4B show the upper lead terminal 3.
5A is a plan view and FIG. 5B is a side view of the lower lead terminal 3b. FIG. In FIG. 4, the upper lead terminal 3a has a length a = 3.1 mm from the side surface to the tip of the upper case 2a, and a width b = b at the tip.
0.4 mm. Similarly, in FIG. 5, the length of the lower lead terminal 3b from the tip to the lower case 2b is f = 3.
1 mm, and the width at the tip is g = 0.4 mm.

Upper lead terminal 3a and lower lead terminal 3
The width of the mold insert portion b is expanded to c = h = 1.0 mm in order to have strength as a spring material. The material of the lead terminal is phosphor bronze (C-521).
0H material), the plate thickness d = i = 0.1 mm, and 2-5
A μm nickel plating was applied. The step at the tip of the lead terminal 3 is e = 0.45 mm for the upper lead terminal 3a and j = 0.6 mm for the lower lead terminal (all include the thickness d = i = 0.1 mm of the lead terminal 3). Lead terminal 3
The dimension of the contact portion of the upper lead terminal 3a (contact length) L is L = b = 0.4 m
m, the contact area S at the lower lead terminal 3b is S = 0.2
5 mm ² . The contact of the lead terminal 3 with the piezoelectric transformer element 1 is achieved by pushing the upper and lower strokes of about 0.
5 mm, and the pressing force was set to 50 to 60 gf.

In all the embodiments described below, the piezoelectric transformer element 1, the case 2, the lead terminals 3a,
3b is the above-mentioned size and shape.

The elastic adhesive 4 is a white sealer (trade name, manufactured by HOLTS, a silicone adhesive excellent in elasticity and adhesiveness, hardness after formation: 30 to 80 (JI)).
SK6253))) was used. In this embodiment, the elastic adhesive 4 has a coating volume of 0.25 ml to 0.7.
Controlled in the range of 5 ml, to adjust the contact area of the piezoelectric transformer element 1 and the elastic adhesive 4 after assembly formed to be 0.5 mm ² 1.5 mm ² per one place.

The piezoelectric transformer obtained with the above configuration was subjected to noise level evaluation, electrical characteristic evaluation, vibration / shock test, and reliability test. The following results were obtained.

First, when the noise level was measured, the conventional product (FIG. 12) generated a few dB to 10 dB larger than the background level (occurrence rate: about 30%). Background level.

Next, when the electric characteristics were evaluated, the energy conversion efficiency was 95% or more, which was a good result without any difference from the conventional configuration in which only the lead terminals were used.

Subsequently, the holding force was evaluated by a vibration / impact test. Vibration test is 3G, 15Hz-1kHz
Was performed with 20 samples per cycle for one minute and 120 cycles (2 h) in each direction with respect to the XYZ directions of the piezoelectric transformer (360 cycles in total, 6 cycles).
h). The noise level measurement and the electrical characteristics after the vibration test were not different from the initial values, and were good results.

In addition, the distance from the ± XYZ directions of the piezoelectric transformer is 1
00G (approximately 10 msec) shocks 10 times each (6 times in total)
(0 times) Even in the applied impact test (the number of samples: 20), a change in noise level and electrical characteristics did not occur before and after the impact test, and a piezoelectric transformer having reliability against external stress was realized. .

Furthermore, reliability tests were conducted on high-temperature storage, low-temperature storage, and thermal shock storage (20 samples each). However, no problems such as an increase in the noise level of the piezoelectric transformer and a decrease in energy conversion efficiency occurred. In addition, a piezoelectric transformer that is reliable against environmental changes has been realized.

In the same evaluation as above, the contact area between the piezoelectric transformer element 1 and the elastic adhesive 4 was smaller than 0.5 mm ² per location (specifically, the application volume of the elastic adhesive 4 was 0.1 mm).
When the amount was less than 25 ml), the energy conversion efficiency as electrical characteristics was as good as in the present invention, but the noise level was evaluated.
Noise occurred at an incidence of about 5%. In addition, vibration and impact tests were performed to evaluate the noise level after each test. As a result, noise was generated at an incidence of about 15%.

In the same evaluation, the contact area between the piezoelectric transformer element 1 and the elastic adhesive 4 is larger than 1.5 mm ² per one place (specifically, the applied volume of the elastic adhesive 4 is set to 0.1 mm).
When the noise level was evaluated, no noise was generated in the same manner as in the present invention, and vibration and impact tests, high-temperature storage, low-temperature storage, thermal shock storage, and the like were performed. Even after the test was performed, there was no increase in noise level, but the energy conversion efficiency was reduced to 90% or less as an electrical characteristic.

Regarding the hardness of the material of the elastic adhesive 4, 30
When the lower device was evaluated, the result was too soft to hold the device sufficiently. In addition, evaluation was made of a material having a hardness greater than 80 (hard), and as a result, the result was that the energy conversion efficiency was as low as 90% or less as electrical characteristics.

The above is the case where a silicone-based material is used. Similar results were obtained when a urethane-based material was used.

[Second Embodiment] FIG. 6 is an exploded perspective view for explaining a second embodiment of the present invention.

The second embodiment is different from the first embodiment shown in FIG. 1 in that an electrode at the center of the piezoelectric transformer element 1 is formed in common on the front and back surfaces, and the lower lead terminal 3b is formed. One of the three is that the middle one is eliminated, and the position where the elastic adhesive 4 is applied is the center of the piezoelectric transformer element in the length direction.

[Second Embodiment] The above-mentioned white sealer was used as the elastic adhesive 4 and applied to the upper case 2b at two locations (all node points) and the lower case 2b at three locations (one non-node point). In this embodiment, the elastic adhesive 4 is
The application volume is controlled in the range of 0.25 ml to 0.75 ml, and the contact area between the piezoelectric transformer element 1 and the elastic adhesive 4 after assembly is 0.5 mm ^{2 to} 1.5 m per location.
It was adjusted to m ^2.

After the piezoelectric transformer was assembled, noise level evaluation, electrical characteristic evaluation, vibration / shock test, and reliability test were performed in the same manner as in the first embodiment. The results were the same as in the first embodiment. Could be obtained.

In the first embodiment, there is a danger that the elastic adhesive 4 adheres to the central lead terminal 3b, causing a change in the pressing force of the lead terminal 3b. In the above, the middle one of the three lower lead terminals 3b is eliminated so that the elastic adhesive 4 can be applied to the middle position, so that the above danger is eliminated and the work of the application / assembly process is performed. Improved.

[Third Embodiment] FIG. 7 is an exploded perspective view for explaining a third embodiment of the present invention, and FIG. 8 shows a positional relationship of each part in the present embodiment. FIG. 9 and FIG. 10 correspond to A in FIG.
It is sectional drawing in the -A 'line and the BB' line. 7 to 10
, The same reference numerals are given to the same parts as those in the previous embodiment shown in FIG. 1 to FIG. 6, and thus the duplicated description will be omitted. The elastic adhesive 4 used in the first and second embodiments is not used,
On the front and back surfaces and side surfaces of the piezoelectric transformer element 1, frustoconical or spheroidal elastic projections are provided by screen printing or the like. That is, the upper elastic projection 6a is provided on the upper surface of the piezoelectric transformer element 1, the lower elastic projection 6b is provided on the lower surface, and the side elastic projection 6c is provided on the side surface, and the cases 2a and 2b are combined from above and below. In FIG. 9, the distal ends of the elastic projections are illustrated as being in contact with the inner surface of the case. However, since the piezoelectric elements themselves are supported by the lead terminals, all of the piezoelectric elements need not be in contact.

[Third Embodiment] FIG. 11 is a plan view, a side view and a sectional view showing the positions of elastic projections 6a, 6b and 6c printed on the piezoelectric transformer element 1. As shown in FIG. 11, the elastic projections include a total of six points (including two non-node points) on the upper and lower surfaces of the piezoelectric transformer element 1, a total of four points (no non-node points) on the long side, and a short side. 2 points on the side (all non-node points)
A total of 12 points were provided. Next, the elastic projections 6a, 6b, 6
The dimension of c will be described. The upper elastic projection 6a provided on the upper surface of the piezoelectric transformer element 1 had a diameter k = 1.0 mm and a height m = 0.35 mm. Similarly, the lower elastic projection 6b provided on the lower surface of the piezoelectric transformer element 1 has a diameter n = 1.
0, height p = 0.25 mm, the side elastic projection 6c provided on the side surface of the piezoelectric transformer element 1 has a truncated cone shape with an elliptical bottom surface, the major axis q of the ellipse q = 1.0 mm, and the minor axis length r = 0.
5 mm and height s = 0.1 mm. These elastic projections may be made of an elastic material having no adhesive property such as silicon rubber or urethane rubber, and have a hardness of 30 to 80 (JIS K).
6253).

With these elastic projections, the piezoelectric transformer 1 does not come into direct contact with the case 2, and a piezoelectric transformer with very low sound generation during operation can be realized. Also,
In the first and second embodiments, the piezoelectric transformer element 1 and the case 2 are bonded. However, in this embodiment, the piezoelectric transformer element 1 is not bonded to the case 2. Especially the elastic protrusion 6
By maintaining a clearance of about 0.03 to 0.1 mm as a gap between the piezoelectric transformer element 1 and the case 2, a piezoelectric transformer having excellent electrical characteristics without vibration constraint of the piezoelectric transformer element 1 can be realized. In this embodiment, as in the first and second embodiments, the piezoelectric transformer element 1 is not only pressed by the lead terminals 3a and 3b, but is also protected by the elastic projections. A highly reliable piezoelectric transformer can be realized.

In the piezoelectric transformer obtained in this embodiment, the noise level during operation, electrical characteristics, vibration / shock test, and reliability test were performed in the same manner as in the first and second embodiments. Good results similar to those of the first and second embodiments were obtained.

In contrast to the first and second embodiments, in the third embodiment, the elastic projection can be formed by adjusting the printing amount by screen printing or the like. This is advantageous in that the projection height can be adjusted according to the gap between them. It goes without saying that the elastic projections need to be formed of a material having a lower hardness than the insulating case.

Fourth Embodiment As a fourth embodiment, the elastic projections 6a and 6b of the third embodiment are removed, and only the side elastic projection 6c is formed on the side surface of the piezoelectric transformer element. . Then, elastic adhesive was applied to the upper case and the lower case at two and three places, respectively, as in the first embodiment, and the upper and lower surfaces of the piezoelectric transformer element were bonded to the case (however, the adhesive was piezoelectric). It did not go around the side of the transformer element.) The number of the side elastic protrusions 6c was the same as the size of the protrusion 6c in the third embodiment and the same number (total of 6 points).

The piezoelectric transformer obtained in this embodiment was subjected to a noise level during operation, an electrical characteristic, a vibration / shock test, and a reliability test. The same good results as in the other embodiments were obtained. Was.

[0042]

As described above, in the piezoelectric transformer of the present invention, the piezoelectric transformer element is pressed and held by the lead terminal at the node point, and the vibration node point and the vibration non-node point are connected to the insulating case. Since the elastic member is interposed therebetween, the following effects can be obtained.

Since the piezoelectric transformer element does not come into direct contact with the case but is held by the lead terminals having elasticity and held or protected by the elastic member, the frequency of the frequency in the audible sound range is applied to the piezoelectric transformer element. Even when vibration occurs, the vibration becomes difficult to propagate to the case, and the noise level generated when the piezoelectric transformer operates can be reduced.

Even when the piezoelectric transformer element is held at a non-node point, the holding member is relatively soft and the contact area is limited, so that the vibration of the piezoelectric transformer element is not hindered, and A piezoelectric transformer having excellent characteristics can be supplied.

Even when vibration or shock is applied from the outside, the piezoelectric transformer element does not move with respect to the case, so that the contact point of the lead terminal with the piezoelectric transformer element moves from the node point, thereby lowering the conversion efficiency. Disappears.

For the same reason as described above, the contact of the piezoelectric transformer element with the case is prevented, and the noise caused by the contact of the piezoelectric transformer element with the case can be prevented.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view for explaining a first embodiment of the present invention.

FIG. 2 is a plan view for explaining the first embodiment of the present invention.

FIG. 3 is an enlarged view of a cross section of a lower case for describing an adhesive fixing method according to the first embodiment of the present invention.

FIG. 4 is a plan view and a side view of an upper lead terminal for explaining an embodiment of the present invention.

FIG. 5 is a plan view and a side view of a lower lead terminal for explaining the embodiment of the present invention.

FIG. 6 is an exploded perspective view for explaining a second embodiment of the present invention.

FIG. 7 is an exploded perspective view for explaining a third embodiment of the present invention.

FIG. 8 is a plan view for explaining a third embodiment of the present invention.

FIG. 9 is a sectional view taken along line AA ′ of FIG. 8;

FIG. 10 is a sectional view taken along the line BB ′ in FIG. 8;

FIG. 11 is a plan view, a side view in a long side direction, and a sectional view in a short side direction of a piezoelectric transformer element for explaining a third embodiment of the present invention.

FIG. 12 is a longitudinal sectional view and a transverse sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11 Piezoelectric transformer element 1a, 1b Electrode 2 Case 2a, 12a Upper case 2b, 12b Lower case 3a, 13a Upper lead terminal 3b, 13b Lower lead terminal 4 Elastic adhesive 5 Snap fit finger 6a Upper elastic protrusion 6b Lower elastic Projection 6c Side elastic projection 14 Projection N node area

Claims (10)

[Claims] 1. A piezoelectric transformer, comprising: a piezoelectric transformer element having electrodes formed on upper and lower surfaces of a plate-shaped piezoelectric body; and an insulating case for housing the piezoelectric transformer element via lead terminals. Are pressed from the upper and lower surfaces by the lead terminal at the vibration node point, and the insulation elasticity is provided between the vibration node points and the vibration non-node points on the upper and lower surfaces and side surfaces of the piezoelectric transformer element and the insulation case. A piezoelectric transformer, wherein a member is interposed. 2. The method according to claim 1, wherein the insulating elastic member is provided at a vibration node point on a line passing through a node point of the piezoelectric transformer element and parallel to a side of the piezoelectric transformer element or at a vibration non-node point in the vicinity thereof. The piezoelectric transformer according to claim 1, wherein 3. The insulating elastic member is made of an elastic adhesive applied to upper and lower surfaces of the insulating case, and the elastic adhesive extends around a side surface of the piezoelectric transformer element. The piezoelectric transformer according to claim 1. 4. The piezoelectric transformer according to claim 1, wherein the insulating elastic member is constituted by elastic protrusions formed on four side surfaces and upper and lower surfaces of the piezoelectric transformer element. 5. The insulating elastic member comprises an elastic adhesive applied to upper and lower surfaces of the insulating case, and elastic protrusions formed on four side surfaces of the piezoelectric transformer element. The piezoelectric transformer according to claim 1, wherein 6. The insulating elastic member is made of a silicone or urethane material and has a hardness of 30 to 80.
2. The piezoelectric transformer according to claim 1, wherein the piezoelectric transformer conforms to JIS K6253. 7. A contact area of the insulating elastic member with the piezoelectric transformer element is 0.5 to 1.5 mm ² per one place.
The piezoelectric transformer according to claim 1, wherein 8. An electrode formed at the center of the upper and lower surfaces of the piezoelectric body is connected to a side surface of the piezoelectric body, and an electrode formed continuously on the upper and lower surfaces is provided with a lead terminal only on one side of the upper and lower surfaces. 2. The piezoelectric transformer according to claim 1, wherein the piezoelectric transformers are in contact with each other. 9. The piezoelectric transformer according to claim 4, wherein a gap is maintained between the elastic projection and the insulating case. 10. The piezoelectric transformer according to claim 9, wherein the gap is about 0.03 to 0.1 mm.