JP2002286746A - Method of manufacturing for piezoelectric sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing for a small piezoelectric sensor with high detecting sensitivity of angular acceleration and translational acceleration in high productivity. SOLUTION: A stacked body is obtained by stacking first and second piezoelectric members 100, 200 on each side of a supporting member 300. The supporting member 300 has a plurality of projection parts 301 formed in the same position on both surfaces in the thickness direction. Each of the projection parts 301 extends in a strip shape in the length direction L at intervals of width direction W. In the first and second piezoelectric members 100, 200, one end in the width direction W is bonded to one of adjacent two projection parts 301, the other end is extended in the opposite direction and separated at the distance SL1 from one of adjacent two projection parts 301. The stacked body is cut in the X direction perpendicularly crossing to the length direction L, and on the cut surface, cut treatment in the crossing two directions is conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a piezoelectric sensor used for an acceleration sensor or the like.

[0002]

2. Description of the Related Art Piezoelectric sensors of this type are used for detecting acceleration and impact in, for example, a hard disk drive, an airbag system, an electronically controlled suspension system, and the like. It is extremely important that the number of points is small, the size is small, and the mass productivity is excellent. It is also important to have a function that can detect both angular acceleration and translational acceleration.

As a piezoelectric sensor having a function of detecting both angular acceleration and translational acceleration, for example, Japanese Patent Application Laid-Open No.
Japanese Patent Application Laid-Open No. 104164/2000 and Japanese Patent Application Laid-Open No. 2000-171480 are known. JP-A-7-1
The acceleration sensor disclosed in Japanese Patent No. 04164 uses two piezoelectric elements having electrodes on both side surfaces, and arranges the two piezoelectric elements in a straight line with their longitudinal directions coinciding.
It has a structure in which opposite ends are cantilevered by an insulating support member. The piezoelectric sensor element disclosed in Japanese Patent Application Laid-Open No. 2000-171480 has basically the same structure.

However, in the above-described prior art, since the two piezoelectric elements are arranged in a straight line with their longitudinal directions coincident with each other, and the ends facing each other are cantilevered by an insulating support member. The assembly structure is complicated, the number of parts is large, and mass productivity cannot be said to be excellent. In addition, since the two piezoelectric elements are arranged in a straight line with their longitudinal directions aligned, it is difficult to reduce the size. In order to reduce the size, each of the two piezoelectric elements must be shortened, and the angular acceleration sensitivity is reduced.

[0005] As another means, a method of detecting angular acceleration by using two independent acceleration sensors is also known. However, in this case, a difference in output signal between the two acceleration sensors occurs due to a difference in characteristics between the acceleration sensors, a difference in environment due to the installation position, for example, a temperature difference, and the like, so that the angular acceleration can be accurately calculated. It is difficult to detect.

[0006]

An object of the present invention is to provide a manufacturing method suitable for manufacturing a piezoelectric sensor having a function of detecting both angular acceleration and translational acceleration.

Another object of the present invention is to provide a manufacturing method suitable for manufacturing a piezoelectric sensor which is small and has high detection sensitivity for angular acceleration and translational acceleration.

[0008]

In order to solve the above-mentioned problems, a piezoelectric sensor which is a subject of a manufacturing method according to the present invention includes a first piezoelectric element, a second piezoelectric element, and a support member. The first and second piezoelectric elements are arranged substantially in parallel at an interval from each other, one ends of which are opposite to each other are supported by the support member, and the other ends are free ends.

In this piezoelectric sensor, the first and second piezoelectric elements are arranged substantially in parallel at an interval from each other, so that the two piezoelectric elements are arranged in a straight line with the longitudinal directions thereof coincident. The length can be reduced as compared with the conventional structure.

In addition, the shortening of the length is not caused by shortening the length of each of the first and second piezoelectric elements, but by the parallel arrangement of two piezoelectric elements.
There is no deterioration in detection sensitivity.

Further, since the first and second piezoelectric elements have opposite ends supported by a support member and the other end is a free end, the first and second piezoelectric elements are located between the first and second piezoelectric elements. By properly selecting and connecting the electrodes,
Angular acceleration and translational acceleration can be detected simply and reliably.

A manufacturing method according to the present invention for manufacturing the above-described piezoelectric sensor includes a laminating step and a cutting step.

[0013] The laminating step comprises the steps of:
This is a step of obtaining a laminate including the piezoelectric member and the support member. The support member includes a plurality of protrusions at the same position on both surfaces, and each of the protrusions extends in a strip shape in the length direction at intervals from one another in the width direction.

The first piezoelectric member extends on one surface of the support member in a longitudinal direction of the convex portion, and one end in the width direction is supported by one of the two adjacent convex portions, and the other end is formed by the other end. An interval is provided between the adjacent two convex portions.

The second piezoelectric member extends in the length direction of the projection on the other surface of the support member, and has one end in the width direction supported by one of the two adjacent projections, and the other end in the width direction. The other end of the first piezoelectric member extends in the opposite direction and is spaced apart from the other of the two adjacent protrusions.

[0016] In the cutting step, the laminate is cut in a direction orthogonal to the length direction.
A step of performing a cutting process in two orthogonal directions.

According to the above-described manufacturing method, a small-sized piezoelectric sensor having a function of detecting both angular acceleration and translational acceleration can be manufactured with high productivity.

Other objects, configurations and advantages of the present invention will be described in more detail with reference to the accompanying drawings. However, the attached drawings are merely examples.

[0019]

FIG. 1 is a perspective view of a piezoelectric sensor according to the present invention, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG. 3 is a view of a sensor part of the piezoelectric sensor shown in FIG. It is a top view.
The illustrated piezoelectric sensor includes a first piezoelectric element 10 and a second piezoelectric element 10.
A piezoelectric element 20, a support 30, a first lid 50,
And a second lid 60.

The first piezoelectric element 10 comprises two piezoelectric elements 1
1 and 12 are stacked such that the polarization directions P11 and P12 are reversed. The piezoelectric bodies 11 and 12 are made of piezoelectric ceramics. The first piezoelectric element 10 has a first electrode 13 and a second electrode 14 on both surfaces in the thickness direction parallel to the lamination surface. The common electrode 15 is provided on the lamination surface.

The second piezoelectric element 20 also includes two piezoelectric elements 2
1 and 22 are laminated such that the polarization directions P21 and P22 are reversed. The piezoelectric bodies 21 and 22 are made of piezoelectric ceramics. The second piezoelectric element 20 has a third electrode 23 and a fourth electrode 24 on both surfaces in the thickness direction parallel to the lamination surface. The common electrode 25 is provided on the lamination surface.

The first and second piezoelectric elements 10 and 20 are arranged substantially in parallel at an interval from each other, and one ends opposite to each other are supported by a support 30 and the other ends are free ends. In the illustrated embodiment, the first piezoelectric element 10 and the second piezoelectric element 20 are arranged such that the first electrode 13 of the first piezoelectric element 10 faces the fourth electrode 24 of the second piezoelectric element 20. , Are arranged substantially in parallel.

The support 30 has a frame shape. The illustrated support 30 includes a first support 31 and a second support 32.
And a third support 33. First to third support members 3
Reference numerals 1 to 33 are made of electrically insulating ceramic or plastic. Examples of usable materials include ceramics such as forsterite, cordierite, and magnesium titanate, and heat-resistant resins such as liquid crystal polymers.

One end of the first piezoelectric element 10 is sandwiched and joined between the end of the first support 31 and the end of the third support 33. An interval having the same thickness as the first piezoelectric element 10 is provided between the first support 31 and the third support 33 on a side opposite to a side where one end of the first piezoelectric element 10 is sandwiched. The regulating member 35 is sandwiched and joined.

One end of the second piezoelectric element 20 is opposite to the one end of the first piezoelectric element 10 on the second support 32.
And the end of the third support 33,
And are joined. A space having the same thickness as the second piezoelectric element 20 is provided between the second support 32 and the third support 33 on the side opposite to the side holding one end of the second piezoelectric element 20. The regulating member 34 is sandwiched and joined.

The second support 32 is provided on the second piezoelectric element 20.
The first terminal electrode 71 is provided on the side surface on the side that sandwiches.
The first terminal electrode 71 is connected to the third
The electrode 23 is electrically connected. The third support 33 is
A second terminal electrode 72 is provided on a side surface on which the second piezoelectric element 20 is sandwiched. The second terminal electrode 72 is electrically connected to the fourth electrode 24 of the second piezoelectric element 20.

The first support 31 is provided on the first piezoelectric element 10.
A third terminal electrode 73 is provided on the side surface on the side that sandwiches.
The third terminal electrode 73 is connected to the second
The electrode 14 is electrically connected. Further, the third support 3
3 has a fourth terminal electrode 74 on the side surface opposite to the second terminal electrode 72. The fourth terminal electrode 74 is electrically connected to the first electrode 13 of the first piezoelectric element 10.

First to fourth electrodes 13, 14, 23, 2
The fourth and first to fourth terminal electrodes 71 to 74 are formed by printing, sputtering, vapor deposition, plating, or the like.

The first and second lids 50 and 60 secure a space for the first and second piezoelectric elements 10 and 20 to vibrate, and the first and second piezoelectric elements 10 and 20 and The first to third support members 31 to 33 are disposed on both sides of the assembly. The first and second lids 50 and 60 are
And concave portions (51, 52) and (61, 62) for securing a vibration space for the second piezoelectric elements 10 and 20, respectively. The first and second lids 50 and 60 are provided with first to third lids.
, For example, ceramics such as forsterite, cordierite and magnesium titanate, or a heat-resistant resin such as a liquid crystal polymer. The first and second lids 50 and 60 are made of a first conductive material with a non-conductive adhesive.
The third support members 31 to 33 are bonded to both surfaces in the thickness direction. On the surfaces of the first and second lids 50 and 60,
First to fourth terminal electrodes 71 to 74 are provided.

In the piezoelectric sensor of the embodiment, the first and second piezoelectric elements 10 and 20 are arranged substantially parallel to each other with an interval therebetween, so that the two piezoelectric elements are aligned in the longitudinal direction. The length can be shortened as compared with the conventional structure in which they are arranged in a straight line.

Moreover, the shortening of the length is not caused by shortening the length of each of the first and second piezoelectric elements 10 and 20, but by the parallel arrangement of the two piezoelectric elements 10 and 20. The detection sensitivity does not deteriorate.

Also, a pair of piezoelectric bodies (11, 12), (2
1, 22) are polarization directions (P11, P12), (P2
1, P22) are superposed so as to be opposite to each other, so that noise due to temperature fluctuation can be canceled.

FIG. 4 is a view for explaining the angular acceleration detecting operation by the piezoelectric sensor shown in FIGS. As shown in FIG. 4, when an angular acceleration is applied to the piezoelectric sensor, the first piezoelectric element 10 and the second piezoelectric element 20 apply a force Ra in the opposite direction.
Acts, a level difference is generated between the response signal obtained at the second electrode 14 and the response signal obtained at the fourth electrode 24 with reference to the first and third electrodes 13 and 23. . Therefore, an angular acceleration response signal can be obtained using the level difference between the response signals of the second electrode 14 and the fourth electrode 24. In the case of the embodiment, the angular velocity response signal is the second
From the electrode terminal 72 and the third electrode terminal 73.

FIG. 5 is a diagram for explaining the translational acceleration detecting operation by the piezoelectric sensor shown in FIGS. When a translational acceleration is applied, a force La in the same direction is applied to the first piezoelectric element 10 and the second piezoelectric element 20, so that the second electrode 14 and the fourth electrode 24 have the same polarity. Is obtained. A response signal obtained at the second electrode 14;
The level difference between the response signal obtained at the fourth electrode 24 becomes almost zero. Therefore, the translational acceleration can be detected using the response signals generated at the second electrode 14 and the fourth electrode 24.

In a practical circuit connection, the fourth terminal 74 electrically connected to the first electrode 13 and the third electrode 23 are electrically connected. The specific means are as follows:
A method of electrically connecting a terminal 74 that has made the electrode 13 conductive and a terminal 71 that has made the third electrode 23 conductive by a conductor pattern on the circuit board, and an outer surface of the second support 32. The terminal 71 and the terminal 74 are electrically connected to each other by the conductive film formed as described above. Although not shown, the first piezoelectric element 10 and the second piezoelectric element 2
0 may be arranged at an angle.

FIGS. 6 to 13 are views showing the steps of a method for manufacturing the piezoelectric sensor shown in FIGS. The manufacturing method according to the present invention includes a lamination step and a cutting step. In the present invention, laminating includes a process of bonding two members to be laminated with an appropriate adhesive. 6 to 13, FIGS. 6 to 8 show a lamination process, and FIGS. 9 to 11 show a cutting process. The process illustrated in FIG. 7 is actually the same process as FIG. 6, but is illustrated separately from the process in FIG. 6 due to space limitations.

The laminating step shown in FIGS.
00, the first piezoelectric element member 100 is laminated on one surface of both surfaces as viewed in the thickness direction, and the second piezoelectric element member 20 is formed on the other surface.
0 is laminated. More specifically, the first piezoelectric element member 100 is laminated on one surface of the opposing surfaces of the support member 300, and the second piezoelectric element member 20 is formed on the other surface.
0 is laminated. Further, another supporting member 300 is laminated on the second piezoelectric element member 200, and the other supporting member 300
Another first piezoelectric element member 100 is laminated on the above. This step is repeated as many times as necessary. The support member 310 is laminated on the lowermost first piezoelectric element member 100. The support member 320 is laminated on the uppermost second piezoelectric element member 200.

The first piezoelectric element member 100, the second piezoelectric element member 200, and the supporting members 300 to 320 have a large size from which a large number of piezoelectric sensors can be taken out. Each of the first and second piezoelectric elements 100 and 200 has a plate shape or a strip shape, each of which is a laminate of two piezoelectric bodies, and has a reverse polarization direction (see FIGS. 1 to 5). . The laminated body having such a polarization direction is, for example, a method of bonding two polarized piezoelectric bodies so that the polarization directions are opposite to each other, and a method of laminating two unpolarized piezoelectric bodies. ,
It can be obtained by performing a polarization treatment.

The support member 300 has a plurality of projections 301 formed at the same position on both surfaces in the thickness direction. Each of the protrusions 301 extends in the width direction W at intervals from each other and extends in the length direction L in a strip shape. Two adjacent projections 30
A strip-shaped recess 302 exists between 1 and 301. Each of the support members 310 and 320 has a convex portion 301 and a concave portion 302 only on one side which is a laminated surface. Support members 300 to 32
0 can be made of, for example, ceramics such as forsterite, cordierite, and magnesium titanate, or a heat-resistant resin such as a liquid crystal polymer.

In the illustrated embodiment, the first piezoelectric element member 100 has a strip shape, and each of the first piezoelectric element members 100 has a support member 300.
Is supported by the protrusion 301.
The first piezoelectric element member 100 has one end in the width direction W stacked on one of the two adjacent protrusions 301 and the other end separated from the other of the two adjacent protrusions 301 by an interval SL1. I have. The same applies to the relationship with the support member 310.

The second piezoelectric element member 200 is also in the shape of a strip, and each is supported by a projection 301 on the other surface of the support member 300. Second piezoelectric element member 2
00 is laminated on one of the two convex portions 301 having one end in the width direction W adjacent thereto, and the other end extends in the opposite direction to the other end of the first piezoelectric element member 100 and has two adjacent convex portions. 301
Is separated from the other by an interval SL2. Support member 32
The same applies to the relationship with 0.

Although not shown, the first and second piezoelectric element members 100 and 200 are one large plate piezoelectric element member substantially equal to the plane area of the support member 300, and
After laminating on one surface and the other surface of the support member 300, slits may be linearly formed along the boundary between the concave portion 302 and the convex portion 301 of the support member 300 to form the intervals SL1, SL2. Even if such a step is taken, the supporting member 300
When viewed from above, the arrangement is as shown in FIG.

FIG. 8 is a perspective view of the laminated assembly obtained through the laminating step shown in FIG. As shown in FIG. 8, the laminated assembly 700 is cut along a cutting line X orthogonal to the length direction L. The set interval of the cutting line X depends on the thickness dimension of the piezoelectric sensor to be obtained. FIG. 9 is a perspective view of a cut piece 710 obtained through the above-described cutting step.

Next, a first lid 500 and a second lid 600 are provided on both sides in the thickness direction of the cut piece 710 shown in FIG.
After laminating with an adhesive, as shown in FIG.
Cut along the cutting line Y. The cutting line Y is
The projections 301 of 0 to 320 are set at positions where they are divided into two.

Next, as shown in FIG. 11, the obtained cut piece 720 is cut along a cutting line X1 orthogonal to the cutting line Y. The cutting line X1 is set at a position where the obtained final cut piece includes two piezoelectric elements, that is, the first and second piezoelectric elements. Before or after the cutting step of FIG.
In addition, fourth to fourth terminal electrodes 71 to 74 (see FIGS. 1 to 5) are provided. Thereby, the individual product of the piezoelectric sensor shown in FIGS. 1 to 5 is obtained.

FIG. 12 is a perspective view showing another example of the laminating step included in the method for manufacturing a piezoelectric sensor according to the present invention. In the figures, the same reference numerals as those shown in FIGS. 6 to 11 indicate the same components. In the laminating step illustrated in FIG. 12, the plate-shaped first piezoelectric element member 100 is laminated on one surface of both surfaces in the thickness direction of the first support member 330.

Separately from this, a plate-shaped second piezoelectric element member 20 is provided on one of the opposite surfaces of the second support member 340.
0 are stacked.

Then, the first piezoelectric element member 100 laminated on the first support member 330 and the second support member 3
The third support member 350 is disposed between the second piezoelectric element member 200 and the second piezoelectric element member 200 stacked on the first support member 40, and the first piezoelectric element member 100 is stacked on one surface of the third support member 350. The second piezoelectric element member 200 is laminated on the other surface of the third support member 350.

Although not shown, in the case of a multi-layer lamination, the required number of units can be combined with the combination of FIG. 12 as one unit. Also,
As the cutting step, the steps shown in FIGS. 9 to 11 are applied.

FIG. 13 is a perspective view showing still another example of the lamination step included in the method for manufacturing a piezoelectric sensor according to the present invention. In the figures, the same reference numerals as those shown in FIGS. 6 to 11 indicate the same components.

In the laminating step shown in FIG. 13, the first piezoelectric element 10
0 and stacking the second piezoelectric element member 200 on the other surface of the support member 300 to obtain an assembly 730. The assemblies 730 and the fourth support members 360 thus obtained are alternately arranged and stacked. As the cutting step, the steps shown in FIGS. 9 to 11 are applied.

Although the present invention has been described with reference to the preferred embodiments, it is obvious to those skilled in the art that the present invention can be variously modified in accordance with the basic concept and scope.

[0053]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a manufacturing method capable of manufacturing a piezoelectric sensor having a function of detecting both angular acceleration and translational acceleration with good mass productivity. (B) It is possible to provide a manufacturing method capable of manufacturing a small-sized piezoelectric sensor having high detection sensitivity for angular acceleration and translational acceleration with good mass productivity.

[Brief description of the drawings]

FIG. 1 is a perspective view of a piezoelectric sensor obtained by applying a manufacturing method according to the present invention.

FIG. 2 is a sectional view taken along line 2-2 in FIG.

FIG. 3 is a plan view of a sensor portion of the piezoelectric sensor shown in FIG.

FIG. 4 is a diagram illustrating an angular acceleration detection operation by the piezoelectric sensor shown in FIGS.

FIG. 5 is a diagram illustrating a translational acceleration detecting operation by the piezoelectric sensor shown in FIGS. 1 to 3;

FIG. 6 is a view illustrating a process of manufacturing the piezoelectric sensor illustrated in FIGS. 1 to 5;

FIG. 7 is a view showing the same step as the step shown in FIG. 6;

FIG. 8 is a view showing a step after the step shown in FIGS.

FIG. 9 is a view showing a step after the step shown in FIG. 6;

FIG. 10 is a view showing a step after the step shown in FIG. 9;

FIG. 11 is a view showing a step that follows the step shown in FIG. 10;

FIG. 12 is a perspective view showing another example of the laminating step included in the method for manufacturing a piezoelectric sensor according to the present invention.

FIG. 13 is a perspective view showing another example of the lamination step included in the method for manufacturing a piezoelectric sensor according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 First piezoelectric element member 200 Second piezoelectric element member 300, 310, 320 Support member 330 First support member 340 Second support member 350 Third support member 360 Fourth support member

Claims (7)

[Claims] 1. A method of manufacturing a piezoelectric sensor including a laminating step and a cutting step, wherein the piezoelectric sensor includes a first piezoelectric element, a second piezoelectric element, and a support. The first and second piezoelectric elements are arranged substantially in parallel at an interval from each other, one end of each of the first and second piezoelectric elements opposite to each other is supported by the support, and the other end is a free end. Is a step of obtaining a laminate including a first piezoelectric member, a second piezoelectric member, and a support member, wherein the support member includes a plurality of convex portions at the same position on both surfaces, and the convex portion Are respectively extended in the length direction at intervals in the width direction, and the first piezoelectric member is formed on one surface of the support member.
Extending in the length direction of the protrusion, one end in the width direction is supported by one of the two adjacent protrusions, the other end is spaced from the other of the two adjacent protrusions, The second piezoelectric member may include, on the other surface of the support member,
Extending in the length direction of the protrusion, one end in the width direction is supported by one of the two adjacent protrusions, the other end extends in the opposite direction to the other end of the first piezoelectric member, An interval is provided between the adjacent two convex portions, and the cutting step cuts the laminate in a direction orthogonal to the length direction, and further, in a cut surface, in two orthogonal directions. A manufacturing method including a step of performing a cutting process. 2. The manufacturing method according to claim 1, wherein the laminating step includes a step of repeatedly laminating the first piezoelectric member, the support member, and the second piezoelectric member. Production method. 3. The manufacturing method according to claim 1, further comprising: the support member, first to third support members, and wherein the laminating step is performed on one surface of the first support member. Laminating the first piezoelectric member, laminating the second piezoelectric member on one surface of the second support member, between the first piezoelectric member and the second piezoelectric member, Disposing the third support member, laminating the first piezoelectric member on one surface of the third support member, and laminating the second piezoelectric member on the other surface of the third support member Manufacturing method including steps. 4. The manufacturing method according to claim 1, wherein in the laminating step, the first piezoelectric member is laminated on one surface of the support member,
A manufacturing method comprising: laminating the second piezoelectric member on the other surface of the support member to form an assembly; and alternately laminating the assembly and another support member. 5. The manufacturing method according to claim 1, wherein in the laminating step, the plurality of strip-shaped first and second piezoelectric members are arranged side by side on the support member. A manufacturing method including a step of arranging and attaching. 6. The manufacturing method according to claim 1, wherein in the laminating step, a large-plate piezoelectric member having a plane area substantially equal to a plane area of the support member is replaced with the support member. And then forming a slit on the large-plate piezoelectric member so as to be independent as the first piezoelectric member and the second piezoelectric member, and forming the gap. 7. The manufacturing method according to claim 1, wherein the first and second piezoelectric members are a stacked body including two piezoelectric bodies, and wherein the two piezoelectric members are stacked. Manufacturing method in which the polarization direction of the body is reversed.