JP2003215152A - Piezoelectric sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric sensor that can be enhanced incharge sensitivity, and reduced in size. <P>SOLUTION: A piezoelectric element 2 contains electrode films 21-27, and piezoelectric ceramic layers 11-16. The piezoelectric ceramic layers 11-16 are provided with at least four layers or more, and layered each other while sandwiching the electrode films 22-26 therebetween. The first support member 3 has the first protruded part 31, and the second support member 4 has also the second protruded part 41. The first support member 3 and the second support member 4 are arranged to make the first protruded part 31 face to the second protruded part 41 each other with a space. The piezoelectric element 2 is arranged between the first protruded part 31 and the second protruded part 41 to be sandwiched by end faces of the first protruded part 31 and the second protruded part 41. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art This type of piezoelectric sensor is used for detecting acceleration and impact in, for example, a hard disk drive device, an air bag system, an electronically controlled suspension system, etc. Small number and small size are extremely important.

[0003] As a known document example disclosing a technique meeting such requirements, for example, Japanese Patent Laid-Open No. 8-29447,
JP-A-9-54111 and JP-A-9-26490
No. 1 publication etc. In the disclosed technology of these known documents, the base member is provided with a recess and an element mounting portion, and the piezoelectric element is fixed to the element mounting portion. The piezoelectric element is arranged in the element mounting portion so that a space is formed between the side surface and the bottom surface of the recess.

By the way, in the technology disclosed in the above-mentioned known documents,
A bimorph piezoelectric element is used as the piezoelectric element.
The bimorph piezoelectric element is formed by, for example, stacking and joining two single-plate piezoelectric elements. In this type of bimorph piezoelectric element, it is difficult to increase the charge sensitivity because the electrostatic capacity is relatively small.

If a large capacitance is to be secured in order to increase the charge sensitivity, the bimorph piezoelectric element must be upsized, and the piezoelectric sensor incorporating the bimorph piezoelectric element is also upsized.

[0006]

An object of the present invention is to provide a piezoelectric sensor which can improve the charge sensitivity.

Another object of the present invention is to provide a piezoelectric sensor which can be miniaturized.

[0008]

In order to solve the above problems, a piezoelectric sensor according to the present invention includes a piezoelectric element, a first supporting member, and a second supporting member.

The piezoelectric element includes an electrode film and a piezoelectric ceramic layer. The piezoelectric ceramic layer has at least 4
More than one layer is provided, and they are laminated on each other with the electrode film interposed therebetween.

The first support member has a first protrusion. The second support member has a second protrusion. The first support member and the second support member are arranged such that the first projecting portion and the second projecting portion face each other with a space therebetween.

The piezoelectric element is arranged between the first projecting portion and the second projecting portion and is sandwiched by the end faces of the first projecting portion and the second projecting portion.

As described above, in the piezoelectric sensor according to the present invention, the first support member and the second support member are the first support member and the first support member.
And the second protrusion are arranged to face each other with a space therebetween. The piezoelectric element is arranged between the first projecting portion and the second projecting portion and is sandwiched by the end faces of the first and second projecting portions. Therefore, when an exciting force, an impact, or the like is applied, in the piezoelectric element, the part around the part sandwiched by the first and second protrusions is deformed in response to the exciting force, and a detection signal is generated. To do.

Further, as an important feature of the present invention, in the piezoelectric element, at least four or more piezoelectric ceramic layers are laminated on each other with the electrode film interposed therebetween. By using these four or more piezoelectric ceramic layers, it is possible to secure a large electrostatic capacitance and thereby improve the charge sensitivity.

Moreover, by using four or more piezoelectric ceramic layers, a large capacitance can be secured without increasing the size of the piezoelectric element. Therefore, it is possible to avoid an increase in the size of the piezoelectric sensor incorporating the piezoelectric element and reduce the size of the piezoelectric sensor.

In the piezoelectric element, some of the electrode films may be connected through through holes provided in the piezoelectric ceramic layer. By using through holes, complicated interlayer connection of electrode films can be easily realized.

As one specific mode, in the piezoelectric element, an intermediate portion in the longitudinal direction is sandwiched by the end faces of the first and second projecting portions. When an exciting force, an impact, or the like is applied in this mode, in the piezoelectric element, the portions on both sides of the intermediate portion sandwiched by the first and second projecting portions are deformed in response to the exciting force.

As another specific mode, in the piezoelectric element, one end in the lengthwise direction is sandwiched by the end faces of the first and second protrusions. In this mode, when a vibration force, a shock, or the like is applied, the piezoelectric element is deformed in response to the vibration force at the other end portion of the one end portion sandwiched by the first and second protrusions.

In a preferable configuration of the piezoelectric sensor according to the present invention, the first supporting member has the first contact electrode on the end face of the first protruding portion, and the second supporting member also has the second protruding member. A second contact electrode is provided on the end surface of the portion. In the piezoelectric element, electrode films are provided between the layers of the piezoelectric ceramic layers and on both outer surfaces of the laminated body of the piezoelectric ceramic layers, and the electrode films on both outer surfaces are electrically connected to the first and second contact electrodes by the sandwiching. Has been conducted to. According to this structure, the detection signal generated in the piezoelectric element when applying a vibration force, a shock, or the like is extracted to the outside from the electrode films on both outer surfaces via the first and second contact electrodes.

Other objects, structures 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.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an exploded perspective view of a piezoelectric sensor according to the present invention, FIG. 2 is a perspective view showing the external appearance of the piezoelectric sensor shown in FIG. 1, and FIG. 3 is a piezoelectric view shown in FIGS. FIG. 4 is a plan view of the sensor with the lid member omitted, FIG. 4 is a sectional view taken along line 4-4 of FIG. 3, and FIG. 5 is a sectional view taken along line 5-5 of FIG. As illustrated, the piezoelectric sensor according to the present invention includes a piezoelectric element 2, a first supporting member 3, and a second supporting member 4.

First, referring to FIGS. 1, 3 and 4, the piezoelectric element 2 includes a piezoelectric ceramic layer 11 to 16 and an electrode film 2.
1-27, and has a predetermined width and extends in the length direction. The piezoelectric ceramic layers 11 to 16 are provided in at least four layers and are laminated on each other with the electrode films 22 to 26 interposed therebetween. In the illustrated embodiment, the piezoelectric ceramic layers 11-16
Is equipped with 6 layers. Piezoelectric ceramic layers 11-16
Is made of a material such as lead zirconate titanate.

Of the electrode films 21 to 27, the electrode films 22 to 2
6 is provided between the layers of the piezoelectric ceramic layers 11 to 16. Specifically, these electrode films 22 to 26 are formed between the layers (11, 12) to (15, 1) of the adjacent piezoelectric ceramic layers.
6). The other electrode films 21 and 27 are provided on both outer surfaces of the laminated body including the piezoelectric ceramic layers 11 to 16.

Still referring to FIG. 3, polarization directions P1 to P6 are set in the piezoelectric ceramic layers 11 to 16.
The polarization direction P1 of the piezoelectric ceramic layer 11 is a direction from the electrode film 22 to the electrode film 21. The polarization direction P2 of the piezoelectric ceramic layer 12 is from the electrode film 22 to the electrode film 23.
The direction is toward. The polarization direction P3 of the piezoelectric ceramic layer 13 is from the electrode film 24 toward the electrode film 23. Polarization direction P4 of the piezoelectric ceramic layer 14
Is in the direction from the electrode film 24 to the electrode film 25. The polarization direction P5 of the piezoelectric ceramic layer 15 corresponds to the electrode film 2
The direction is from 6 to the electrode film 25. The polarization direction P6 of the piezoelectric ceramic layer 16 is a direction from the electrode film 26 to the electrode film 27.

Further, connection conductors 81 to 83 are provided in the laminated body of the piezoelectric ceramic layers 11 to 16. Specifically, the connection conductors 81 and 82 are provided on one end surface of the laminated body as viewed in the length direction, and the connection conductor 83 is provided on the other end surface of the laminated body. The above-described electrode films 21 and 23 are connected to each other via the connection conductor 81. Similarly, the electrode films 25 and 27 are also connected to each other via the connection conductor 82, and the electrode films 22, 24 and 26 are also connected to each other via the connection conductor 83.

Next, referring to FIGS. 1 and 3 to 5, the first supporting member 3 has a first projecting portion 31. The first protruding portion 31 is provided in the middle portion in the length direction. Furthermore,
The first support member 3 has first recesses 32 and 33, and the first recesses 32 and 33 extend in the lengthwise direction on both sides of the first protrusion 31. The first support member 3 can be made of electrically insulating ceramic, plastic, or the like. Examples of materials that can be used include ceramics such as forsterite, cordierite, and magnesium titanate, and resins having heat resistance such as liquid crystal polymers.

Further, the first supporting member 3 has a first contact electrode 34 and a first lead electrode 35. The first contact electrode 34 is the first protrusion 31 facing the piezoelectric element 2.
It is provided on the end face of. The first lead electrode 35 is provided on the surface of the first support member 3, specifically, on the bottom surface of the first recess 32, and is electrically connected to the first contact electrode 34. First contact electrode 34 and first lead electrode 35
Are formed by printing, sputtering, vapor deposition or plating.

Similar to the above-mentioned first support member 3,
The second support member 4 also has a second protrusion 41. The second protruding portion 41 is provided in the middle portion in the length direction. Further, the second support member 4 also has second recesses 42 and 43, and the second recesses 42 and 43 extend in the lengthwise direction on both sides of the second protrusion 41. Second support member 4
Can also be made of the same material as the first support member 3.

Further, the second supporting member 4 also has a second contact electrode 44 and a second lead electrode 45. The second contact electrode 44 has a second protrusion 41 facing the piezoelectric element 2.
It is provided on the end face of. The second lead electrode 45 is provided on the surface of the second support member 4, specifically, on the bottom surface of the second recess 43, and is electrically connected to the second contact electrode 44. Second contact electrode 44 and second lead electrode 45
Is also formed by printing, sputtering, vapor deposition or plating.

The first support member 3 and the second support member 4 described above are arranged so that the first projecting portion 31 and the second projecting portion 41 face each other with a space therebetween. Moreover, the first support member 3 and the second support member 4 are arranged so that their length directions are aligned. Further, in the first support member 3 and the second support member 4, the first recess 32 and the second recess 42 face each other with a space therebetween. Similarly, the other first recess 33 and the other second recess 43 also face each other with a space therebetween.

Next, referring to FIGS. 3 to 5, the piezoelectric element 2 described above is disposed between the first protrusion 31 and the second protrusion 41, and the first and second protrusions are provided. It is sandwiched by the end faces of 31 and 41. More specifically, the piezoelectric element 2 is arranged between the first projecting portion 31 and the second projecting portion 41 in the length direction of the first supporting member 3 and the second supporting member 4, and has a length of The middle portion in the direction is the first and second protrusions 31,
It is sandwiched by the end faces of 41. Both ends of the piezoelectric element 2 in the length direction are free ends.

In the case of the embodiment, the first contact electrode 34 is provided on the end surface of the first protrusion 31, and the second protrusion 4 is provided.
Since the second contact electrode 44 is provided on the end face of 1,
Due to the sandwiching, the electrode films 21 and 27 on both outer surfaces of the laminate are formed.
Is electrically connected to the first and second contact electrodes 34 and 44 (see FIGS. 3 and 4). Electrode film 2 of piezoelectric element 2
The first and second contact electrodes 34 and 44 and the first and second contact electrodes 27 and 27 are bonded by a conductive adhesive or the like.

Further, the piezoelectric element 2 is
The first and second recesses (32, 33) and (42, 43) are arranged at a distance D1 from the bottom surface. The distance D1 is set from the end surface of the first protrusion 31 to the first recess 3
It is determined by the depth to the bottom surfaces of the second and third portions 33 and the depth from the end surface of the second protruding portion 41 to the bottom surfaces of the second concave portions 42 and 43.

Here, the distance D1 is such that even if the end portion in the lengthwise direction of the piezoelectric element 2 is deformed to a position where it touches the bottom surface of the first recesses 32, 33 or the bottom surfaces of the second recesses 42, 43. The size of the piezoelectric element 2 is set so as not to be broken. Interval D
The size of 1 varies depending on the length of the piezoelectric element 2. The larger the length of the piezoelectric element 2, the larger it must be.

In the illustrated embodiment, the first projecting portion 31 and the second projecting portion 41 are inclined surfaces whose end faces are parallel to each other and inclined in the same direction. Therefore, the piezoelectric element 2 is arranged to be inclined. First recesses 32, 33
And the bottom surfaces of the second recesses 42 and 43 are also inclined surfaces that are inclined in the same direction as the end surfaces of the first protruding portion 31 and the second protruding portion 41. Therefore, the piezoelectric element 2 is arranged over the entire length thereof with a distance D1 from the bottom surfaces of the first recesses 32 and 33 and the bottom surfaces of the second recesses 42 and 43.

Alternatively, the first protrusion 31 and the second protrusion 41 may be vertical surfaces whose end faces are parallel to each other. In this case, the piezoelectric element 2 is arranged almost vertically. The bottom surfaces of the first recesses 32 and 33 and the bottom surfaces of the second recesses 42 and 43 are the same as the first protrusion 31.
And a vertical surface parallel to the end surface of the second protrusion 41.

Still referring to FIGS. 1, 2 and 4, the illustrated piezoelectric sensor includes a first lid member 5 and a second lid member 6. The first and second lid members 5 and 6 secure a space for the vibration of the piezoelectric element 2 so that the piezoelectric element 2 and the first
The support member 3 and the second support member 4 are arranged on both surface sides orthogonal to the assembly direction of the assembly. The first and second lid members 5 and 6 have concave portions 51 and 61 for securing a vibration space of the piezoelectric element 2, respectively. The first and second lid members 5 and 6 include the first and second support members 3 and 4, respectively.
The same material as described above, for example, ceramics such as forsterite, cordierite and magnesium titanate, or a resin having heat resistance such as liquid crystal polymer can be used. First and second lid members 5, 6
Is made of a non-conductive adhesive, so that the first support member 3 and the second support member 3
Are adhered to both sides of the support member 4 in the thickness direction.

Further, two terminal electrodes 91 and 92 are provided on the surfaces of the first and second lid members 5 and 6. 1
The one terminal electrode 91 is electrically connected to the first lead electrode 35 through the side surface electrode 95. The other terminal electrode 92 also passes through the side surface electrode 96 and passes through the second lead electrode 45.
Electrically connected to.

Still referring to FIGS. 1 and 3, the illustrated piezoelectric sensor includes a first spacer 98 and a second spacer 99.
Includes and. The first spacers 98 and the second spacers 99 fill gaps between both ends of the first support member 3 and the second support member 4 in the lengthwise direction. In the illustrated embodiment, the first support member 3 has the protrusions 36 and 37 at the same plane position as the end face of the first protrusion 31 at both ends in the longitudinal direction, and Support member 4
Also has protrusions 46 and 47 at the same plane position as the end face of the second protrusion 31 at both ends in the length direction. Therefore, as the first spacer 98 and the second spacer 99, those having the same structure and thickness as the piezoelectric element 2 are used. The first spacer 98 and the second spacer 99 are made of a conductive adhesive or a non-conductive adhesive to form the protrusions 36 and 37 of the first support member 3 and the protrusions 46 and 47 of the second support member 4. Glued to.

Further, the first spacer 98 has the electrode (conductor) provided on the surface thereof, so that the first lead electrode 35 is formed.
To the side surface electrode 95 (see FIG. 3). Similarly,
The second spacer 99 also connects the second lead electrode 45 to the side surface electrode 96 by the electrode (conductor) provided on the surface thereof.

As described above, in the piezoelectric sensor according to the present invention, the first support member 3 and the second support member 4 are
The 1st protrusion part 31 and the 2nd protrusion part 41 are arrange | positioned so that it may mutually oppose and may face. The piezoelectric element 2 is arranged between the first protrusion 31 and the second protrusion 41,
It is sandwiched by the end faces of the first and second protrusions 31 and 41. Therefore, when an exciting force, an impact or the like is applied, the piezoelectric element 2 is deformed in the peripheral portion of the portion sandwiched by the first and second projecting portions 31 and 41 in response to the exciting force. Generate a detection signal.

Further, as an important feature of the present invention, the piezoelectric element 2 includes at least four piezoelectric ceramic layers 11 to 11.
16 are laminated on each other with the electrode films 22 to 26 sandwiched therebetween. By using these four or more piezoelectric ceramic layers 11 to 16, it is possible to secure a large electrostatic capacitance, and thus it is possible to improve the charge sensitivity.

Moreover, four or more piezoelectric ceramic layers 11 are provided.
By using ~ 16, it is possible to secure a large capacitance without increasing the size of the piezoelectric element 2. For this reason,
The piezoelectric sensor incorporating the piezoelectric element 2 is prevented from being upsized, and the piezoelectric sensor can be downsized.

In the illustrated embodiment, the piezoelectric element 2 is sandwiched by the end faces of the first and second projecting portions 31 and 41 at the intermediate portion in the longitudinal direction. Therefore, when an exciting force, a shock, or the like is applied, the piezoelectric element 2 will move to the first and second protruding portions 31, 4
The portions on both sides of the intermediate portion sandwiched by 1 are deformed in response to the excitation force and output a detection signal.

Specifically, the first projecting portion 31 of the first supporting member 3 is provided at the intermediate portion in the length direction,
Also in the second support member 4, the second protruding portion 41 is provided at the middle portion in the length direction. The piezoelectric element 2 described above is
The first and second support members 3 and 4 are arranged between the first and second projecting portions 31 and 41 in the length direction. Therefore, the middle portion in the length direction of the piezoelectric element 2 is set to the first and second portions.
It is easy to obtain a structure in which it is sandwiched by the protruding portions 31 and 41.

Further, in the illustrated embodiment, the first support member 3
Has first recesses 32, 33, and the first recess 3
2, 33 extend in the length direction on both sides of the first protrusion 31. Similarly, the second support member 4 also has second recesses 42 and 43, and the second recesses 42 and 43 also extend in the lengthwise direction on both sides of the second protrusion 41.
Therefore, the piezoelectric element 2 can be disposed over the entire length of the piezoelectric element 2 with a space D1 between the bottom surfaces of the first and second recesses (32, 33) and (42, 43). Therefore, in the piezoelectric element 2, a space is secured for the portions on both sides of the intermediate portion sandwiched by the first and second projecting portions 31 and 41 to be deformed.

Here, the distance D1 is such that even if the end of the piezoelectric element 2 in the lengthwise direction touches the bottom surface of the first recess 32, 33 or the bottom surface of the second recess 42, 43, The size of the piezoelectric element 2 is set so as not to be broken. Therefore, the piezoelectric element 2 responds to excessive vibration force and impact force.
When is deformed, before the piezoelectric element 2 is broken, the end in the lengthwise direction comes into contact with the bottom surface of the first recess 32, 33 or the bottom surface of the second recess 42, 43. Piezoelectric element 2
Cannot be transformed any further. Therefore, the piezoelectric element 2
Will be reliably protected from breakage, chipping or cracking.

Further, as shown in the illustrated embodiment, the end faces of the first projecting portion 31 and the second projecting portion 41 are parallel to each other,
Moreover, in the case where the piezoelectric elements 2 are inclined surfaces that are inclined in the same direction and the piezoelectric elements 2 are arranged so as to be inclined, it is possible to obtain a piezoelectric sensor that responds to impacts and excitation forces in two directions.

FIG. 6 is an equivalent circuit diagram of the piezoelectric sensor shown in FIGS. In terms of an equivalent circuit, the piezoelectric element 2 of the piezoelectric sensor 1 includes a pair of piezoelectric elements 201 and 202. One piezoelectric element 201 is composed of the piezoelectric ceramic layers 11 to 13 and the electrode films 21 to 24 included in the piezoelectric element 2 (see FIG. 3). Another piezoelectric element 201
Is the piezoelectric ceramic layers 14-16 and the electrode films 24-27.
(See FIG. 3).

As described with reference to FIGS. 1, 3 and 4, the first supporting member 3 is provided with the first contact electrode 34 on the end face of the first protruding portion 31, and the second supporting member 3 is provided. The support member 4 of
A second contact electrode 44 is provided on the end surface of the second protrusion 41. The piezoelectric element 2 includes the electrode film 2 of the electrode films 21 to 27.
1, 27 are provided on both outer surfaces of the laminated body including the piezoelectric ceramic layers 11 to 16, and the electrode films 21 and 27 on both outer surfaces are electrically connected to the first and second contact electrodes 34 and 44 by the sandwiching. It is conducted. According to this structure, the detection signal generated in the piezoelectric element 2 when applying a vibration force, a shock or the like is transmitted from the electrode films 21 and 27 on both outer surfaces to the outside via the first and second contact electrodes 34 and 44. It is taken out (see FIG. 6).

Further, the first support member 3 is provided with a first lead electrode 35 on its surface, and the first lead electrode 35 is electrically connected to the first contact electrode 34. Therefore, an electrical path from the first contact electrode 34 to the outside is easily configured (see FIG. 6). In the embodiment, the first contact electrode 34
To the terminal electrode 91 via the first lead electrode 35 and the side surface electrode 95 sequentially.

Similarly, the second support member 4 is also provided with the second lead electrode 45 on the surface thereof, and the second lead electrode 4
Since 5 is electrically connected to the second contact electrode 44,
An electrical path from the second contact electrode 44 to the outside is easily realized (see FIG. 6). In the embodiment, the second contact electrode 4
An electrical path is formed from 4 to the terminal electrode 92 via the second lead electrode 45 and the side surface electrode 96 in sequence.

Next, a method of manufacturing the piezoelectric sensor shown in FIGS. 1 to 5 will be described with reference to FIGS. First, as shown in FIG. 7, on the lowermost layer support member 300,
The piezoelectric element member 200 and the spacer members 980 and 990 are placed. Then, the piezoelectric element member 200 and the spacer member 9
The operation of placing the intermediate support member 100 on 80 and 990 and further placing the piezoelectric element member 200 and the spacer members 980 and 990 on it is repeated. Then, finally, the uppermost layer support member 400 is placed on the piezoelectric element member 200 and the spacer members 980 and 990. Each overlay surface is
It is fixed by adhesion with a conductive adhesive. Bottom layer support member 3
00, the intermediate support member 100, the uppermost layer support member 400, and the piezoelectric element member 200 have a length such that many piezoelectric sensors can be taken out. In comparison with FIGS. 1 to 5, the lowermost layer support member 300 is, for example, the first support member 3 (see FIGS.
(See FIG. 5), and the uppermost layer support member 400 becomes the second support member 4. The intermediate support member 100 is divided into a first support member 3 and a second support member 4.

On the lowermost layer support member 300, a first protrusion 310 is formed on the upper surface side on which the piezoelectric element member 200 and the spacer members 980 and 990 are placed, and the first protrusion 31 is formed.
First concave portions 320 and 330 are formed on both sides of 0. Further, the first contact electrode 3 is formed on the surface of the first protrusion 310.
40 is formed.

A second projecting portion 410 is formed on the lowermost surface of the uppermost layer supporting member 400 which overlaps with the piezoelectric element member 200 and the spacer members 980 and 990, and the second projecting portion 41 is formed.
Second recesses 420 and 430 are formed on both sides of 0. Further, a second contact electrode (not shown) is formed on the surface of the second protrusion 410.

The intermediate support member 100 has a first protrusion 310 formed on the upper surface thereof, and first recesses 320 and 330 formed on both sides of the first protrusion 310. Furthermore the first
The first contact electrode 340 is formed on the surface of the protruding portion 310. A second protrusion 410 is formed on the lower surface side of the intermediate support member 100, and a second protrusion 410 is formed on both sides of the second protrusion 410.
The recesses 420 and 430 are formed. Further, a second contact electrode (not shown) is formed on the surface of the second protrusion 410. FIG. 8 is a perspective view of a laminated assembly obtained through the laminated assembly process shown in FIG.

Next, as shown in FIG. 9, a cutting and dividing step is performed on the laminated assembly shown in FIG. In cutting and dividing, the laminated assembly is subdivided in the lengthwise direction along the cutting line X-X. Thereby, the piezoelectric sensor assembly is obtained. FIG. 10 shows piezoelectric sensor assemblies Q1 to Q3 obtained through the cutting and dividing step shown in FIG. 9, and FIG. 11 is a perspective view of the obtained piezoelectric sensor assembly Qr.

Next, as shown in FIG. 12, the first lid member 500 and the second lid member 500 are formed on both surfaces of the piezoelectric sensor assembly in the thickness direction.
The lid member 600 is adhered. Terminal electrodes 910 and 920 are formed on the upper surface (in the figure) of the first lid member 500, and recesses (not shown) are formed on the lower surface. A terminal electrode (not shown) is formed on the lower surface (in the drawing) of the second lid member 600, and the recess 6 is formed on the upper surface.
10 are arranged at intervals. As a result,
An assembly as shown in 3 is obtained.

Next, side electrodes 950 and 960 are applied to the assembly shown in FIG. Side electrode 95
0 and 960 are formed by means of printing, sputtering, plating or the like.

After this, as shown in FIG. 13, the cutting line Y--Y
The subassembly along its length along its length. As a result, a single piezoelectric sensor is obtained. After that, a side surface electrode or the like is applied to obtain a finished product of the piezoelectric sensor shown in FIGS.

FIG. 14 is a partial sectional view showing another embodiment of the piezoelectric sensor according to the present invention. In the figure, components that are substantially the same as those shown in FIGS. 1 to 5 are designated by the same reference numerals, and redundant description will be omitted as much as possible.

In this embodiment, the piezoelectric ceramic layers 11 to 11 are
A through hole is provided in 16. For example, the piezoelectric ceramic layer 11 is provided with a through hole 86, and the piezoelectric ceramic layer 12 is provided with a through hole 87. The through hole 86 of the piezoelectric ceramic layer 11 can be formed by filling the through hole of the piezoelectric ceramic layer 11 with a conductive material. In the illustrated embodiment, the conductor film 88 is provided between the layers of the piezoelectric ceramic layers 11 and 12, and the through hole 86 of the piezoelectric ceramic layer 11 and the through hole 87 of the piezoelectric ceramic layer 12 form the conductor film 88.
Are connected to each other via.

Further, some of the electrode films 21 to 27 are connected to each other through through holes provided in the piezoelectric ceramic layers 11 to 16. For example, the electrode films 21 and 23 are connected to each other through the through hole 86 of the piezoelectric ceramic layer 11 and the through hole 87 of the piezoelectric ceramic layer 12. Similarly, the electrode films 25 and 27 are also connected to each other through the through holes provided in the piezoelectric ceramic layers 15 and 16, and the electrode films 22, 24 and 26 are also provided in the piezoelectric ceramic layers 11 to 16. Are connected to each other through through holes.

As described above, in the piezoelectric element 2, some of the electrode films 21 to 27 have piezoelectric ceramic layers 11 to 1.
6 are connected via through holes.
By using such through holes, the electrode films 21 to 2
The complicated inter-layer connection of 6 can be easily realized.

FIG. 15 is an exploded perspective view showing still another embodiment of the piezoelectric sensor according to the present invention, FIG. 16 is a perspective view showing the appearance of the piezoelectric sensor shown in FIG. 15, and FIG. 17 is FIG. 15 and FIG.
A plan view of the piezoelectric sensor shown in FIG.
18 is a sectional view taken along the line 18-18 of FIG.
FIG. 19 is a sectional view taken along the line 19-19 in FIG. In the figure, components that are substantially the same as those shown in FIGS. 1 to 5 are designated by the same reference numerals, and redundant description will be omitted as much as possible.

First, referring to FIG. 17, in the illustrated piezoelectric element 2, the polarization direction P1 of the piezoelectric ceramic layer 11 is determined.
Is in the direction from the electrode film 22 to the electrode film 21. The polarization direction P2 of the piezoelectric ceramic layer 12 is the electrode film 2
The direction is from 2 to the electrode film 23. The polarization direction P3 of the piezoelectric ceramic layer 13 is the direction from the electrode film 24 to the electrode film 23. Piezoelectric ceramic layer 14
The polarization direction P4 of is the direction from the electrode film 25 to the electrode film 24. Polarization direction P of the piezoelectric ceramic layer 15
5 is in the direction from the electrode film 25 to the electrode film 26. The polarization direction P6 of the piezoelectric ceramic layer 16 is the direction from the electrode film 27 to the electrode film 26.

Next, referring to FIGS. 15 and 17 to 19, in the illustrated first support member 3, the first protrusion 3 is formed.
1 is provided at one end in the length direction. First recess 3
2 extends in the length direction from the first protrusion 31. First
The contact electrode 34 is provided on the end surface of the first protrusion 31 facing the piezoelectric element 2. First lead electrode 35
Is provided on the surface of the first support member 3, specifically, on the bottom surface of the first recess 32, and is electrically connected to the first contact electrode 34.

In the illustrated second supporting member 4, the second projecting portion 41 is provided at one end portion in the length direction. Second
The recess 42 extends from the second protrusion 41 in the length direction. The second contact electrode 44 is a second contact electrode 44 facing the piezoelectric element 2.
It is provided on the end surface of the protruding portion 41. The second lead electrode 45 is formed on the surface of the second support member 4, specifically, the second lead electrode 45.
Is provided on the bottom surface of the recess 42 and is electrically connected to the second contact electrode 44.

Also in this embodiment, the first support member 3
The second support member 4 is arranged such that the first protrusion 31 and the second protrusion 41 are opposed to each other with a space therebetween. Moreover, the first support member 3 and the second support member 4 are arranged so that their length directions are aligned.

Next, referring to FIGS. 17 to 19, the piezoelectric element 2 is aligned with the first supporting member 3 and the second supporting member 4 in the longitudinal direction, and the first projecting portion 31 and the second projecting portion 31 are arranged. Protrusion 41
It is located between and.

Here, an important feature of this embodiment is that one end portion of the piezoelectric element 2 in the lengthwise direction has the first and second protrusions 3
That is, it is sandwiched by the end faces of 1, 41. The other end of the piezoelectric element 2 in the length direction is a free end.

Also in this embodiment, the first protrusion 31
Since the first contact electrode 34 is provided on the end surface of the second protrusion 41 and the second contact electrode 44 is provided on the end surface of the second protrusion 41, the sandwiching makes it possible to form the electrode films 2 on both outer surfaces of the laminate.
1, 27 are electrically connected to the first and second contact electrodes 34, 44 (see FIGS. 17 and 18).

Further, also in this embodiment, the piezoelectric element 2
Over the entire length thereof, the first and second recesses 32, 4
It is arranged at a distance D1 from the bottom surface of No. 2. The distance D1 is determined by the depth from the end surface of the first protrusion 31 to the bottom surface of the first recess 32 and the depth from the end surface of the second protrusion 41 to the bottom surface of the second recess 42. .
The distance D1 is set such that the piezoelectric element 2 is not broken even when the end portion in the length direction of the piezoelectric element 2 is deformed to a position where it touches the bottom surface of the first recess 32 or the bottom surface of the second recess 42. Is set.

Next, the first and second lid members 5 and 6 will be described. Referring to FIGS. 15 and 16, two terminal electrodes 91 and 9 are provided on the surfaces of the first and second lid members 5 and 6.
3 is provided. One terminal electrode 91 is electrically connected to the first lead electrode 35 and the second lead electrode 45 through the side surface electrode 95. Another terminal electrode 93
Is the connection conductor 83 of the piezoelectric element 2 through the side electrode 97.
To be electrically conducted to (see FIG. 17).

Referring to FIGS. 15 and 17, the first spacer 98 fills the gap between the first support member 3 and the second support member 4 on the other end side in the longitudinal direction. In the illustrated embodiment, the first support member 3 has a protrusion 36 at the other end portion in the length direction, and the second support member 4 is provided.
Also has a protrusion 46 at the other end in the length direction. First
The spacer 98 is adhered to the protrusion 36 of the first support member 3 and the protrusion 46 of the second support member 4.

Further, the first spacer 98 has the electrode (conductor) provided on the surface thereof, so that the first lead electrode 35 is formed.
Also, the second lead electrode 45 is electrically connected to the side surface electrode 95 (see FIG. 17).

As described with reference to FIGS. 17 and 18, the piezoelectric element 2 has one end in the lengthwise direction sandwiched by the end faces of the first and second protrusions 31 and 41. Therefore, when an exciting force, an impact, or the like is applied, in the piezoelectric element 2, the portion on the other end side of the one end portion sandwiched by the first and second projecting portions 31 and 41 responds to the exciting force. It deforms and outputs a detection signal.

Specifically, the first projecting portion 31 of the first supporting member 3 is provided at one end portion in the length direction,
Also in the second support member 4, the second protrusion 41 is provided at one end in the length direction. The piezoelectric element 2 described above is
The first and second support members 3 and 4 are arranged between the first and second projecting portions 31 and 41 in the length direction. Therefore, one end of the piezoelectric element 2 in the lengthwise direction is
It is easy to obtain a structure in which it is sandwiched by the protruding portions 31 and 41.

Further, in the illustrated embodiment, the first support member 3
Has a first recess 32, and the first recess 32 has a first
The protrusion 31 extends in the length direction. Similarly, the second
The support member 4 also has a second recess 42, and the second recess 42 also extends in the length direction from the second protrusion 41.
Therefore, the piezoelectric element 2 can be disposed over the entire length of the piezoelectric element 2 with a space D1 between the bottom surfaces of the first and second recesses 32 and 42. Therefore, the piezoelectric element 2 has the first
Also, a space for deforming the other end of the one end sandwiched by the second protrusions 31 and 41 is secured.

Here, as for the distance D1, the end portion in the length direction of the piezoelectric element 2 is the bottom surface of the first concave portion 32 or the second concave portion 4.
The size of the piezoelectric element 2 is set so that the piezoelectric element 2 does not break even when it is deformed to the position where it touches the bottom surface of the piezoelectric element 2. Therefore, when the piezoelectric element 2 is deformed in response to an excessive vibration force or impact force, the end portion in the longitudinal direction of the piezoelectric element 2 is broken before the piezoelectric element 2 is broken.
The bottom surface of the first recess 32 or the bottom surface of the second recess 42 is touched. The piezoelectric element 2 cannot be further deformed. Therefore, the piezoelectric element 2 is reliably protected from breakage, chipping or cracks.

FIG. 20 is an equivalent circuit diagram of the piezoelectric sensor shown in FIGS. In terms of an equivalent circuit, the piezoelectric element 2 of the piezoelectric sensor 1 includes a pair of piezoelectric elements 201 and 202. One piezoelectric element 201 includes piezoelectric ceramic layers 11 to 13 and electrode films 21 to 24 included in the piezoelectric element 2.
(See FIG. 17). The other piezoelectric element 201 includes the piezoelectric ceramic layers 14 to 16 and the electrode film 24.
˜27 (see FIG. 17).

As described with reference to FIGS. 15, 17, and 18, the first support member 3 is also used in this embodiment.
Has a first contact electrode 34 on the end surface of the first protrusion 31, and the second support member 4 also has a second contact electrode 44 on the end surface of the second protrusion 41. The piezoelectric element 2 is
The electrode films 21 and 27 of the electrode films 21 to 27 are provided on both outer surfaces of the laminated body including the piezoelectric ceramic layers 11 to 16,
The electrode films 21 and 27 on both outer surfaces have the first
And electrically connected to the second contact electrodes 34 and 44. According to such a configuration, the detection signal generated in the piezoelectric element 2 when applying a vibration force, a shock, or the like is transmitted to the electrode films 21 on both outer surfaces.
It is taken out from 27 through the first and second contact electrodes 34 and 44 (see FIG. 20).

Further, also in this embodiment, an electrical path from the first contact electrode 34 to the terminal electrode 91 via the first lead electrode 35 and the side surface electrode 95 in sequence, and the second contact electrode An electrical path is formed from 44 to the terminal electrode 91 by sequentially passing through the second lead electrode 45 and the side surface electrode 95 (see FIG. 20).

21 and 22 are views for explaining a method of manufacturing the piezoelectric sensor shown in FIGS. In the figure, components that are substantially the same as those shown in FIGS. 7 to 13 are designated by the same reference numerals, and redundant description will be omitted as much as possible.

First, as shown in FIG. 21, the piezoelectric element member 200 and the spacer member 9 are provided on the lowermost layer supporting member 300.
Put 80. Then, the operation of placing the intermediate support member 100 on the piezoelectric element member 200 and the spacer member 980, and further placing the piezoelectric element member 200 and the spacer member 980 thereon is repeated. And finally, the piezoelectric element member 20
0, the uppermost layer support member 400 is placed on the spacer member 980. In comparison with FIGS. 15 to 19, the lowermost layer support member 300 is, for example, the first support member 3 (see FIGS. 15 to 19).
), The uppermost layer support member 400 becomes the second support member 4. The intermediate support member 100 is divided into a first support member 3 and a second support member 4.

The lowermost layer support member 300 is provided with a first protrusion 310 and a first recess 320 on the upper surface side on which the piezoelectric element member 200 and the spacer member 980 are placed.
A first contact electrode 340 is formed on the surface of the first protrusion 310.

The uppermost layer support member 400 is provided with a second protrusion 410 and a second recess 420 on the lower surface side overlapping the piezoelectric element member 200 and the spacer member 980.
A second contact electrode (not shown) is formed on the surface of the second protrusion 410.

The intermediate support member 100 is provided with a first protrusion 310 and a first recess 320 on the upper surface side.
A first contact electrode 340 is formed on the surface of the first protrusion 310. On the lower surface side of the intermediate support member 100, the second
The protrusion 410 and the second recess 420 are formed. A second contact electrode (not shown) is formed on the surface of the second protrusion 410. FIG. 22 is a perspective view of a laminated assembly obtained through the laminated assembly process shown in FIG.

Subsequent steps are the same as the steps shown in FIGS. 9 to 13, and a duplicate description will be omitted.

Although a plurality of embodiments have been described above,
It is obvious to those skilled in the art that an embodiment obtained by combining these embodiments can be constructed. Further, it is obvious to those skilled in the art that the present invention can be variously modified according to the basic idea and scope.

[0090]

As described above, according to the present invention, the following effects can be obtained. (A) A piezoelectric sensor capable of improving charge sensitivity can be provided. (B) It is possible to provide a piezoelectric sensor that can be miniaturized.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a piezoelectric sensor according to the present invention.

FIG. 2 is a perspective view showing an appearance of the piezoelectric sensor shown in FIG.

FIG. 3 is a plan view of the piezoelectric sensor shown in FIGS. 1 and 2 with a lid member omitted.

4 is a cross-sectional view taken along line 4-4 of FIG.

5 is a sectional view taken along line 5-5 of FIG.

FIG. 6 is an equivalent circuit diagram of the piezoelectric sensor shown in FIGS.

FIG. 7 is a diagram illustrating a method of manufacturing the piezoelectric sensor shown in FIGS.

FIG. 8 is a diagram showing a laminated assembly obtained through the steps shown in FIG. 7.

FIG. 9 is a diagram showing a process of performing cutting division on the laminated assembly shown in FIG. 8;

10 is a diagram showing a piezoelectric sensor assembly obtained through the cutting and dividing step shown in FIG.

11 is a diagram showing a piezoelectric sensor assembly obtained through the cutting and dividing step shown in FIGS. 9 and 10. FIG.

FIG. 12 is a diagram showing a step that follows the step shown in FIGS. 9 to 11.

13 is a diagram showing a terminal electrode applying process and a cutting process after the process shown in FIG.

FIG. 14 is a partial cross-sectional view showing another embodiment of the piezoelectric sensor according to the present invention.

FIG. 15 is an exploded perspective view showing still another embodiment of the piezoelectric sensor according to the present invention.

16 is a perspective view showing the external appearance of the piezoelectric sensor shown in FIG.

FIG. 17 is a plan view of the piezoelectric sensor shown in FIGS. 15 and 16 with a lid member omitted.

18 is a sectional view taken along the line 18-18 of FIG.

FIG. 19 is a sectional view taken along the line 19-19 in FIG.

20 is an equivalent circuit diagram of the piezoelectric sensor shown in FIGS.

FIG. 21 is a diagram illustrating a method of manufacturing the piezoelectric sensor shown in FIGS.

FIG. 22 is a diagram showing a laminated assembly obtained through the process shown in FIG. 21.

[Explanation of symbols]

2 Piezoelectric element 3 First support member 4 Second support member

Claims (11)

[Claims] 1. A piezoelectric sensor including a piezoelectric element, a first support member, and a second support member, wherein the piezoelectric element includes an electrode film and a piezoelectric ceramic layer, and the piezoelectric ceramic layer. Are provided in at least four layers or more and are laminated on each other with the electrode film interposed therebetween, the first support member has a first protrusion, and the second support member is a second The first supporting member and the second supporting member are arranged such that the first protruding portion and the second protruding portion face each other with a space therebetween. The piezoelectric element is arranged between the first projecting portion and the second projecting portion, and is sandwiched by the end faces of the first projecting portion and the second projecting portion. 2. The piezoelectric sensor according to claim 1, wherein some of the electrode films are connected to each other through through holes provided in the piezoelectric ceramic layer. 3. The piezoelectric sensor according to claim 1, wherein the piezoelectric element has the first and second intermediate portions in the longitudinal direction.
A piezoelectric sensor sandwiched by the end faces of the protruding portion of the. 4. The piezoelectric sensor according to claim 3, wherein in the first support member, the first protrusion is provided at an intermediate portion in the length direction, and the second support is provided. In the member, the second protrusion is provided at an intermediate portion in the lengthwise direction, and the piezoelectric element has the first support member and the second support member in the lengthwise direction aligned with each other. A piezoelectric sensor disposed between the protrusion and the second protrusion. 5. The piezoelectric sensor according to claim 4, wherein the first support member further has a first recess, and the first recess is on both sides of the first protrusion. In the length direction, the second support member further has a second recess, and the second recess extends in the length direction on both sides of the second protrusion. Piezoelectric sensor. 6. The piezoelectric sensor according to claim 1, wherein the piezoelectric element has the first and second end portions in the length direction.
A piezoelectric sensor sandwiched by the end faces of the protruding portion of the. 7. The piezoelectric sensor according to claim 6, wherein in the first support member, the first protrusion is provided at one end in the length direction, and the second support is provided. In the member, the second projecting portion is provided at one end portion in the length direction, and the piezoelectric element is aligned with the first supporting member and the second supporting member in the length direction to form the first A piezoelectric sensor disposed between the protrusion and the second protrusion. 8. The piezoelectric sensor according to claim 7, wherein the first support member further has a first recess, and the first recess has a length from the first protrusion. The piezoelectric sensor further has a second recess, and the second recess further extends in a length direction from the second protrusion. 9. The piezoelectric sensor according to claim 5, wherein the piezoelectric element is spaced from the bottom surfaces of the first and second recesses over the entire length of the piezoelectric element. The piezoelectric elements are arranged such that even if the ends in the lengthwise direction of the piezoelectric element touch the bottom surface of the first concave portion or the bottom surface of the second concave portion, the piezoelectric element is broken. Piezoelectric sensor set to a unique dimension. 10. The piezoelectric sensor according to claim 1, wherein the first support member has a first end on the end face of the first protrusion.
The contact electrode is provided, and the second support member has a second end on the end face of the second protrusion.
In the piezoelectric element, the electrode film is provided between layers of the piezoelectric ceramic layer, and on both outer surfaces of a laminated body of the piezoelectric ceramic layers, and the electrode films on both outer surfaces are A piezoelectric sensor electrically connected to the first and second contact electrodes by being sandwiched. 11. The piezoelectric sensor according to claim 10, wherein the first support member has a first lead electrode on a surface thereof, and the first lead electrode is the first contact electrode. The second support member is provided with a second lead electrode on its surface, and the second lead electrode is electrically connected to the second contact electrode. Sensor.