JPH08316543A - Piezoelectric transformer - Google Patents

Abstract

PURPOSE: To obtain a piezoelectric transformer which is capable of being mounted directly on a mounting board and lessened in labor hours required for mounting. CONSTITUTION: A piezoelectric transformer is equipped with a piezoelectric ceramic element 1 where a projection 11 is provided at each node projecting towards a mounting board 6. At this point, the projections 11 may be formed in one piece with the piezoelectric ceramic element 1. A mounting electrode 12 may be previously formed on the projection 11 and connected directly to the connection electrode located on the mounting board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer used for forming an inverter for a backlight of a liquid crystal display.

[0002]

2. Description of the Related Art A piezoelectric transformer converts input electric energy into mechanical energy by a piezoelectric effect, utilizes the piezoelectric effect again, and then converts mechanical energy into electric energy to obtain a boosted high voltage. Yes,
It has been proposed to use the longitudinal effect and the lateral effect based on the relationship between the vibration direction and the polarization direction of the piezoelectric body. Among them, one utilizing the lateral effect is a piezoelectric transformer (hereinafter referred to as a first conventional example) configured as shown in FIG. 6, and this piezoelectric transformer includes PZT (lead zirconate titanate) or the like. A rectangular flat plate-shaped piezoelectric ceramic element 1 manufactured by using (1), and one side along the longitudinal direction (in the figure,
The primary side electrodes 2 for input facing each other along the thickness direction are formed on the main surface of the half part on the left side, while the width direction is formed on the side surface of the half part on the other side (right side in the figure). A secondary electrode 3 for output, which is opposed to the output side electrode 3, is formed.
Each half of the piezoelectric ceramic element 1 is polarized along the required direction by using the primary side and secondary side electrodes 2 and 3.

The piezoelectric transformer in this case is
It is generally mounted in a state as shown in FIG. 7, and when a voltage matching the resonance frequency of the piezoelectric ceramic element 1 is applied to the primary side electrode 2 through the input side lead wire 4, the piezoelectric effect is produced. Causes mechanical vibration, and a high voltage is generated by the piezoelectric effect associated with the mechanical vibration. Therefore, the generated high voltage is taken out from the secondary electrode 3 through the lead wire 5 on the output side. Become. In FIG. 7, reference numeral 6 is a mounting board, 7 is a supporting member, and 8 and 9 are input-side and output-side lands formed on the surface of the mounting board 6, with respect to the input-side land 8. The lead wire 4 on the input side is soldered and connected, while the lead wire 5 on the output side is soldered and connected to the land 9 on the output side. That is, since this piezoelectric transformer has two so-called node points 10 of vibrations, which are indicated by broken lines at the lower position in FIG. Each position corresponding to the node point 10 that does not hinder the vibration of the element 1 is supported by a supporting member 7 made of epoxy resin or the like having a required cross-sectional shape.

As another piezoelectric transformer (hereinafter referred to as a second conventional example), there is an external perspective view of the upper surface side in FIG. 8 and a mounting structure in FIG. Primary side electrodes 2 for input which are opposed to each other along the thickness direction are formed on the main surfaces of one side and the other side half along the longitudinal direction of the piezoelectric ceramic element 1 constituting the transformer, respectively. A secondary electrode 3 for output is formed at a position sandwiched between the primary electrodes 2 on the main surface on one side (upper side in the drawing) of the element 1. In this piezoelectric transformer, as shown by the broken line in FIG. 9, since there are three node points 10, the support member 7 made of epoxy resin or the like is provided at each position corresponding to these node points 10. It is being supported. 8 and 9, parts and portions common to those in FIGS. 6 and 7 are designated by the same reference numerals.

[0005]

By the way, the piezoelectric transformer converts voltage by utilizing mechanical vibration, and the piezoelectric ceramic element 1 repeats mechanical vibration. At the time of supporting, the piezoelectric ceramic element 1 is separated from the surface of the mounting substrate 6 by supporting each position corresponding to the node point 10 with the supporting member 7. However, if such a configuration is adopted, the piezoelectric transformer cannot be directly mounted on the surface of the mounting substrate 6, and the supporting member 7 has to be prepared and mounted. There is an inconvenience in that it sometimes requires troublesome work.

The present invention was devised in view of such inconvenience, and can be directly mounted on a mounting board, and the labor required at the time of mounting can be reduced. The purpose is to provide a piezoelectric transformer.

[0007]

In order to achieve the above-mentioned object, a piezoelectric transformer according to the present invention is provided with protrusions projecting toward the mounting board at each position corresponding to a node point of a piezoelectric ceramic element. It is characterized by being present. In this case, the protrusion may be formed integrally with the piezoelectric ceramic element. It is also possible to form the mounting electrodes on each of the protrusions and solder the mounting electrodes to the connection electrodes on the mounting board.

[0008]

According to the above construction, the protrusion comes into contact with the surface of the mounting board, and the piezoelectric transformer is supported by the protrusion. As a result, a separate supporting member is used. Therefore, it is not necessary to provide support in, and the labor required for mounting can be reduced.

[0009]

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

First Embodiment FIG. 1 is an external perspective view showing the structure of a piezoelectric transformer according to a first embodiment of the present invention, FIG. 2 is a mounting structure diagram showing its mounting state in a simplified manner, and FIG. 2A is an enlarged view of a mounting structure showing a main part indicated by an arrow AA in FIG. 1, and FIG. 1A is an external perspective view of an upper surface side of the piezoelectric transformer as viewed from above. FIG. 6B is an external perspective view of the bottom surface side showing the state of the piezoelectric transformer as viewed from below. 1 to 3, parts and portions which are the same as or equivalent to those in FIGS. 6 to 9 showing the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

The piezoelectric transformer according to this embodiment is called a single plate lateral effect type similar to the first conventional example.
The piezoelectric ceramic element 1 having a rectangular flat plate shape manufactured by using, for example, is provided, and the piezoelectric ceramic element 1 is supported by two node points 10 (see FIG. 8). Then, the piezoelectric ceramic element 1
On one main surface of one side, that is, on the bottom surface located on the mounting board 6 side, at each position corresponding to the node point 10, a protruding portion 11 having a rectangular cross-section that projects toward the mounting board 6 side.
Are integrally formed, and these projections 11 are provided along the width direction of the piezoelectric ceramic element 1.

Therefore, as will be described later, when a piezoelectric transformer having the piezoelectric ceramic element 1 provided with the protrusions 11 on the bottom surface is mounted on the mounting substrate 6, the surface of the mounting substrate 6 is mounted. On the other hand, the protrusion 11 comes into contact with the piezoelectric transformer, and the piezoelectric transformer is directly mounted on the mounting substrate 6 via the protrusion 11. That is, in the piezoelectric transformer according to this embodiment, unlike the conventional example, it is not necessary to provide the support member 7 as a separate member for mounting, and it is not necessary to prepare the support member 7. Each of these protrusions 11 does not necessarily have to be integrated with the piezoelectric ceramic element 1. For example, the protrusions 11 may be manufactured as separate bodies and then attached by adhesion or the like.

Further, on the main surface of a half portion on one side (left side in the figure) along the longitudinal direction of the piezoelectric ceramic element 1 constituting this piezoelectric transformer, the primary side for input opposite along the thickness direction. While the electrode 2 is formed, a secondary electrode 3 for output, which opposes along the width direction, is formed on the side surface of the other half (the right side in the drawing) on the other side. The mounting electrodes 12 are formed on the respective end faces by a technique such as baking or vapor deposition of a conductive paste. At this time, the primary-side electrode 2 on the bottom surface of the piezoelectric ceramic element 1 is formed so as to be separated from the end surface located on the front side of the piezoelectric ceramic element 1, as shown in FIG. 1B. Each of the primary-side electrode 2 and the secondary-side electrode 3 and each of the mounting electrodes 12 are associated with each other and connected.

That is, the primary-side electrode 2 formed on the upper surface of the piezoelectric ceramic element 1 is not limited to the mounting electrode 12 formed on the front side in FIG. The piezoelectric ceramic element 1 is formed on the bottom surface of the piezoelectric ceramic element 1 including the side surface of the protruding portion 11 while being connected to the mounting electrode 12 having a long shape formed even over the side surface of the piezoelectric ceramic element 1. Primary electrode 2
Are associated with the mounting electrodes 13 formed only on the end faces of the protrusions 11 located on the front side in FIG. In addition, each of the secondary electrodes 3 formed on the side surface of the piezoelectric ceramic element 1 has a protrusion 11
Is connected to each of the mounting electrodes 12 formed on the end face of the. Therefore, these primary side and secondary side electrodes 2 and 3 and each of the mounting electrodes 12 are electrically connected to each other by being connected. The piezoelectric ceramic element 1 at this time has been polarized by using the primary side electrode 2 and the secondary side electrode 3 as in the conventional example.

Further, the piezoelectric transformer according to the first embodiment is to be mounted on the mounting substrate 6 in the state shown in FIGS. 2 and 3, and is formed on the protruding portion 11 of the piezoelectric ceramic element 1. Each of the mounting electrodes 12 is soldered to the lands 8 and 9 on the input side and the output side, which are connection electrodes formed on the surface of the mounting substrate 6, and then individually connected. It should be noted that reference numeral 13 in FIG. 3 indicates solder that connects the lands 8 and 9 and the mounting electrode 12.

Therefore, in the piezoelectric transformer having such a mounting structure, a voltage matching the resonance frequency of the piezoelectric ceramic element 1 is applied to the land 8 on the input side and the mounting electrode 1.
When applied to the primary electrode 2 through 2, the piezoelectric effect causes mechanical vibration, and the piezoelectric effect accompanying the mechanical vibration causes a high voltage, resulting in the secondary electrode. From 3, the high voltage is taken out after passing through the mounting electrode 12 and the land 9 on the output side. The piezoelectric ceramic element 1 at this time repeats mechanical vibration, but the piezoelectric transformer is
Piezoelectric ceramic element 1 provided at each position corresponding to
The piezoelectric ceramic element 1 is mounted on the mounting substrate 6 via the protrusion 11 of the piezoelectric ceramic element 1 and is separated from the surface of the mounting substrate 6 except for the node points 10.
The disturbance of the vibration of will not happen.

By the way, in this embodiment, the piezoelectric ceramic element 1 is supported via the projections 11 provided at the positions corresponding to the node points 10 on the bottom surface of the piezoelectric ceramic element 1, and the projections 11 are provided on the respective end surfaces thereof. A mounting structure in which the mounting electrodes 12 are formed and the primary and secondary electrodes 2 and 3 are connected to the lands 8 and 9 via the mounting electrodes 12 is adopted. It is not limited to such a mounting structure. That is, without forming the mounting electrode 12, the primary side and secondary side electrodes 2 and 3 of the piezoelectric ceramic element 1 supported by the protrusions 11 and the lands 8 and 9 on the mounting substrate 6 are the same as in the conventional example. It is also possible to connect with the lead wires 4 and 5 of the above. Even in such a configuration, the original purpose of the present invention is to eliminate the need to use the support member 7 as a separate member. It has been achieved.

Second Embodiment FIG. 4 is an external perspective view showing the structure of a piezoelectric transformer according to a second embodiment of the present invention, and FIG. 5 is a mounting structure diagram showing a simplified mounting state thereof. 4) is an external perspective view of the upper surface of the piezoelectric transformer as viewed from above, and FIG.
(B) is an external perspective view of the bottom surface side showing the state of the piezoelectric transformer viewed from the lower side. 4 and 5, parts and portions which are the same as or correspond to those in FIGS. 1 to 3 showing the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The piezoelectric transformer according to the second embodiment is the second
This is called a single-plate third-order Rosen type similar to the conventional example, and the node points 10 (see FIG. 10) are formed on the main surface on one side of the piezoelectric ceramic element 1 constituting this, that is, the bottom surface located on the mounting substrate 6 side. ), The protrusion 1 having a rectangular cross-section that protrudes toward the mounting substrate 6 side.
1 is integrally formed, and these protrusions 11 are provided along the width direction of the piezoelectric ceramic element 1. In addition, each of the protrusions 11 at this time is
The piezoelectric ceramic element 1 may be manufactured separately and then attached.

Therefore, as will be described later, when a piezoelectric transformer constituted by the piezoelectric ceramic element 1 having these projections 11 provided on the bottom surface is mounted on the mounting substrate 6, it is mounted on the surface of the mounting substrate 6. On the other hand, the protrusion 11 abuts,
The piezoelectric transformer is directly mounted on the mounting board 6 via the protrusion 11. That is, also in this embodiment, it is not necessary to mount the support member 7 as a separate member before mounting. Further, primary side electrodes 2 for input facing each other along the thickness direction are formed on the main surfaces of one side and the other side half along the longitudinal direction of the piezoelectric ceramic element 1 constituting this piezoelectric transformer. On the other hand, the secondary electrode 3 for output is formed on the surface of the protruding portion 11 located at the center of the bottom surface of the piezoelectric ceramic element 1 on the side of the mounting substrate 6, and is mounted on the end surface of each protruding portion 11. The electrode 12 is formed.

At this time, each of the primary-side electrodes 2 on the bottom surface of the piezoelectric ceramic element 1 is on the front side of the piezoelectric ceramic element 1, as shown in FIG. 4B, as in the first embodiment. 4A is connected to each of the mounting electrodes 12 formed only on the end surface of the protruding portion 11 located on the front side in FIG. 4A. In addition, the piezoelectric ceramic element 1
Each of the primary-side electrodes 2 formed on the upper surface of FIG.
The mounting electrode 12 formed on the front side in (b), that is,
While being associated with each of the mounting electrodes 12 having a long shape formed not only on the end faces of the protrusions 11 but also on the side faces of the piezoelectric ceramic element 1, they are connected to each other.
The secondary electrode 3 is connected to the mounting electrode 12 formed on the end surface of the protrusion 11 on which the secondary electrode 3 is formed.

Further, the piezoelectric transformer according to the second embodiment is mounted on the mounting substrate 6 in the state as shown in FIG. 5, and the mounting electrodes 12 formed on the protrusions 11 of the piezoelectric ceramic element 1 are mounted. Are soldered to the input-side and output-side lands 8 and 9 which are connection electrodes formed on the surface of the mounting substrate 6. As a result, the piezoelectric transformer according to the present embodiment is mounted on the mounting substrate 6 via the protrusions 11 of the piezoelectric ceramic element 1 provided at positions corresponding to the node points 10. At this time, Since the portions other than the node points 10 are separated from the surface of the mounting substrate 6, there is no possibility that the vibration of the piezoelectric ceramic element 1 is disturbed. Then, as in the case of the first embodiment, in the piezoelectric transformer according to the second embodiment as well, the mounting electrodes 12 are not formed on the end faces of the respective projections 11 and the mounting substrate is provided via the projections 11. It is possible to connect the primary side and secondary side electrodes 2 and 3 of the piezoelectric ceramic element 1 mounted on 6 to the lands 8 and 9 with lead wires 4 and 5.

By the way, the scope of application of the present invention is not limited to the piezoelectric transformers according to the first and second embodiments, and may be applied to, for example, the well-known Rosen type or those in which these are stacked. Of course, it is applicable.
Although not shown, a piezoelectric transformer whose outer periphery is covered with an insulating layer is also formed if necessary, and a protrusion is attached to the insulating layer of the piezoelectric transformer. Since it can be provided by hand, such a piezoelectric transformer is also included in the scope of application of the present invention.

[0024]

As described above, in the piezoelectric transformer according to the present invention, the protrusions are provided at the positions corresponding to the node points of the piezoelectric ceramic element, and the protrusions are provided directly through these protrusions. As a result, it is not necessary to carry out the mounting using a support member which is a separate member as in the conventional example, and the labor required for mounting can be reduced. Further, when the mounting electrodes are formed on the protrusions, it is possible to obtain an effect that it is not necessary to connect by a lead wire as in the conventional example.

[Brief description of drawings]

FIG. 1 is an external perspective view showing the configuration of a piezoelectric transformer according to a first embodiment.

FIG. 2 is a mounting structure diagram showing a simplified mounting state.

3 is a mounting structure diagram showing an enlarged main part shown by an arrow AA in FIG.

FIG. 4 is an external perspective view showing the configuration of the piezoelectric transformer according to the second embodiment.

FIG. 5 is a mounting structure diagram showing a simplified mounting state.

FIG. 6 is an external perspective view showing a configuration of a piezoelectric transformer according to a first conventional example.

FIG. 7 is a mounting structure diagram showing the mounting state in a simplified manner.

FIG. 8 is an external perspective view showing a configuration of a piezoelectric transformer according to a second conventional example.

FIG. 9 is a mounting structure diagram showing a simplified mounting state.

[Explanation of symbols]

 1 Piezoelectric Ceramic Element 6 Mounting Substrate 8 Land (Connecting Electrode) 9 Land (Connecting Electrode) 10 Node Point 11 Protrusion 12 Mounting Electrode

Claims (3)

[Claims] 1. A piezoelectric transformer, wherein protrusions are provided at positions corresponding to the node points of the piezoelectric ceramic element so as to protrude toward the mounting substrate. 2. The piezoelectric transformer according to claim 1, wherein the protrusion is formed integrally with the piezoelectric ceramic element. 3. A mounting electrode is formed on each of the protrusions, and the mounting electrode is connected to a connection electrode arranged on the mounting substrate.
Alternatively, the piezoelectric transformer according to claim 2.