JPH06201721A - Piezoelectric type vibration sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the detection accuracy in the z-axis direction. [Structure] The film-shaped piezoelectric body 26 and the load body 2 are mounted on the base 21.
5 has a laminated structure. Piezoelectric body 26 and piezoelectric body 2
6, the first electrode 29 arranged over the entire one surface
And a second electrode 31 arranged on the other surface of the piezoelectric body 26 while detecting a potential difference with respect to the first electrode 29. The second electrodes 31 are arranged in a pair on the x-axis,
A pair of x-axis divided electrodes 33 arranged point-symmetrically to each other,
A pair of y-axis divided electrodes 34 formed in the same area as the x-axis divided electrodes and arranged point-symmetrically on the y-axis, and a z-axis electrode whose center is located at the center of the piezoelectric body 26. And 35. The area of the z-axis electrode 35 is 1 to 10 times larger than that of one of the divided electrodes 33 and 34. [Effect] The crosstalk can be suppressed to a low value, and the detection accuracy in the z-axis direction can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibration sensor, and more particularly to a piezoelectric vibration sensor capable of detecting vibrations in the x-axis direction, the y-axis direction, the z-axis direction and these three-dimensional directions by one sensor. It is a thing.

[0002]

2. Description of the Related Art Generally, a piezoelectric vibration sensor is designed to detect vibrations in only one direction, and cannot detect vibrations in other directions. Vibration has a direction and a magnitude, and it is desirable for a vibration sensor to be able to evaluate both of them. Therefore, in order to evaluate all vibrations, the conventional vibration sensor has a structure in which at least three sensors 1, 2 and 3 are combined so that their main sensitivity axes are orthogonal to each other, as shown in FIG. It was necessary to install three detectors so that they were orthogonal to each other. According to such a vibration sensor, it has an extremely complicated structure, becomes costly, requires a large space, and lacks versatility.

The vibration sensor proposed there is, as shown in FIG. 5, a single piezoelectric body 5 mounted on a pedestal,
A load body (not shown) fixed to the upper surface of the piezoelectric body 5,
The first electrode 6 provided on the back surface of the piezoelectric body 5 and the piezoelectric body 5
And a second electrode 4 provided on the surface of the. The first electrode 6 is provided over the entire back surface of the piezoelectric body 6. The second electrode 4 is formed on the surface of the piezoelectric body 5 in a divided manner, and a straight line which is orthogonal to the surface of the piezoelectric body 5 and which passes through substantially the center of the piezoelectric body 5 is the z axis, and the second electrodes 4 are perpendicular to the z axis. A z-axis electrode 7 for detecting displacement in the z-axis direction when two orthogonal straight lines are respectively defined as the x-axis and the y-axis,
It is composed of x-axis electrodes 8 and 9 that detect displacement in the x-axis direction, and y-axis electrodes 10 and 11 that detect displacement in the y-axis direction.

The z-axis electrode 7 is formed in a substantially point-symmetrical shape about the z-axis. x-axis electrodes 8 and 9 are z
A pair of electrodes are formed around the shaft electrode 7 and are line-symmetrical to each other with respect to the y-axis and have the same shape. The y-axis electrodes 10 and 11 are formed around the z-axis electrode 7,
A pair is formed in positions that are line-symmetric with respect to the x-axis and have the same shape. The center of gravity of this vibration sensor is located on an axis passing through the center of the surface of the piezoelectric body 5.

In such a vibration sensor, as shown in FIG. 6, the component of vibration in the z-axis direction is measured based on the potential difference Vz generated between the first electrode 6 and the z-axis electrode 7.
The component of the vibration in the x-axis direction is the potential difference between the potential difference generated between the one x-axis electrode 8 and the first electrode 6 and the potential difference generated between the other x-axis electrode 9 and the first electrode 6. It is measured based on Vx. The y-axis component of vibration is one y
A potential difference generated between the shaft electrode 10 and the first electrode 6,
It is measured based on the difference Vy with the potential difference generated between the other y-axis electrode 11 and the first electrode 6.

[0006]

However, the z-axis electrode 7, the x-axis electrodes 8 and 9, and the y-axis electrodes 10 and 11 are each formed in an area obtained by dividing the surface of the piezoelectric body 5 into nine square areas. Then, the z-axis electrode 7 is arranged at the center of the piezoelectric body 5,
It is considered that the x-axis electrodes 8 and 9 and the y-axis electrodes 10 and 11 are arranged at positions sandwiching the z-axis electrode 7. Therefore, when the position of the load body is displaced and the center of gravity of the vibration sensor is displaced from the center of the piezoelectric body 5 as shown in FIG. 7, the center of gravity of the vibration sensor relative to the length of one side of the square z-axis electrode 7 is reduced. The ratio of the length of misalignment increases, and the z-axis electrode 7
The pressure distribution of the piezoelectric body 5 sandwiched between the first electrode 6 and the first electrode 6 changes.

That is, even if the position of the center of gravity of the vibration sensor deviates slightly from the center of the vibration sensor, in the z-axis electrode 7 having a small span, stress imbalance occurs in the piezoelectric body 5 in the z-axis direction. . Therefore, when vibrating in the x-axis direction or the y-axis direction, the span of the z-axis electrode 7 in the vibrating direction is small. Is increased, the component in the z-axis direction is output, and the vibration sensor detects the component in the z-axis direction, so the detection accuracy of the vibration sensor in the z-axis direction is reduced.

The present invention effectively solves the above problems, and an object thereof is to provide a piezoelectric vibration sensor having improved detection accuracy in the z-axis direction.

[0009]

A piezoelectric vibration sensor according to claim 1 is a piezoelectric vibration sensor having a structure in which a film-shaped piezoelectric body and a load body are laminated on a pedestal. A first electrode disposed over the entire one surface of the piezoelectric body, and a second electrode disposed on the other surface of the piezoelectric body for detecting a potential difference with respect to the first electrode, The second electrodes are arranged in a pair on the x-axis when two straight lines orthogonal to each other with the center of the other surface of the piezoelectric body as the intersection are taken as the x-axis and the y-axis, and are point-symmetrical with respect to the intersection. A pair of divided electrodes for the x-axis and a pair arranged on the y-axis,
A pair of y-axis divided electrodes arranged symmetrically with respect to the intersection, and a z-axis electrode whose center is located at the intersection, the x-axis divided electrode and the y-axis divided electrode. Is formed in the same area and is arranged around the z-axis electrode at equal intervals from the intersection, and the z-axis electrode is one of the x-axis or y-axis split electrodes. On the other hand, 1
It is characterized in that it is formed in an area of 10 times.

A piezoelectric vibration sensor according to a second aspect is a piezoelectric vibration sensor having a structure in which a film-shaped piezoelectric body and a load body are laminated on a pedestal, and the piezoelectric body and one surface of the piezoelectric body. A first electrode disposed over the entire surface, and a second electrode disposed on the other surface of the piezoelectric body for detecting a potential difference with respect to the first electrode, and the second electrode, When two straight lines that are orthogonal to each other with the center of the other surface of the piezoelectric body as an intersection point are defined as an x-axis and a y-axis, a pair of x's are arranged on the x-axis and are point-symmetrical with respect to the intersection. A pair of split electrodes for the axis, a pair of split electrodes for the y-axis, which are arranged in a pair on the y-axis and are point-symmetric with respect to the intersection, and around the split electrode for the x-axis and the split electrode for the y-axis. The z-axis electrode and the y-axis split electrode are the same. The z-axis electrode is 0.125 to 2.5 times as large as one of the x-axis or y-axis split electrodes, and is formed around the intersection. It is characterized by being formed.

[0011]

In the piezoelectric vibration sensor according to the first aspect of the invention, when the vibration is transmitted to the film-shaped piezoelectric body, electric charges are generated in the piezoelectric body. By detecting the potential difference between the first electrode and the second electrode, the charge of the piezoelectric body detects vibrations in the three-dimensional directions of the x-axis, the y-axis, and the z-axis. At this time, since the first electrode is provided over the entire one surface of the piezoelectric body, x is caused by the potential difference generated between the pair of divided electrodes for x axis.
Vibration in the axial direction is detected, vibration in the y-axis direction is detected by the potential difference generated between the pair of split electrodes for the y-axis, and vibration in the z-axis direction is detected by the potential difference between the first electrode and the z-axis electrode. It

If the z-axis electrode has an area which is not more than 1 time the area of one of the x-axis or y-axis split electrodes arranged around the z-axis electrode, then the piezoelectric vibration sensor When the position of the center of gravity of the piezoelectric body is displaced from the center of the piezoelectric body, the ratio of the displacement of the center of gravity of the piezoelectric vibration sensor to the span of the z-axis electrode increases, and the vibration in the x-axis or y-axis direction However, this is not preferable because it detects a potential difference. On the other hand, if the area of the z-axis electrode is formed to be more than 10 times larger than one of the x-axis or y-axis split electrodes, the area of the x-axis or y-axis split electrode is formed to be smaller, Alternatively, when the ratio of the displacement length of the center of gravity of the piezoelectric vibration sensor to the span of the split electrode for the y-axis increases, and the position of the center of gravity of the piezoelectric vibration sensor deviates from the center position of the piezoelectric body, the x-axis The divided electrode for use cannot cancel the vibration in the y-axis direction, and the divided electrode for the y-axis cannot cancel the vibration in the x-axis direction, which is not preferable.

According to another aspect of the piezoelectric vibration sensor of the present invention, when the vibration is transmitted to the film-shaped piezoelectric body, the charges generated in the piezoelectric body are detected by the first electrode and the second electrode. Vibrations in the three-dimensional directions of the x-axis, the y-axis, and the z-axis are detected. At this time, vibration in the x-axis direction is detected by the pair of split electrodes for the x-axis, vibration in the y-axis direction is detected by the pair of split electrodes for the y-axis, and vibration in the z-axis direction is detected by the z-axis electrode. To be done. The x-axis divided electrode and the y-axis divided electrode are formed in the same area and are arranged around the intersection, and the z-axis electrode is formed around the x-axis divided electrode and the y-axis divided electrode. Since it is arranged, the second electrode is arranged over the other surface of the piezoelectric body.

If the area of the z-axis electrode is 0.125 times or less than that of one of the x-axis or y-axis divided electrodes, the center of gravity of the piezoelectric vibration sensor with respect to the span of the z-axis electrode is reduced. When the proportion of the length of the displacement becomes large and the position of the center of gravity of the piezoelectric vibration sensor deviates from the position of the center of the piezoelectric body, the z-axis electrode produces a potential difference with respect to vibration in the x-axis or y-axis direction. It is not preferable because it is detected. On the other hand, if the area of the z-axis electrode is formed to be 2.5 times larger than one of the x-axis or y-axis divided electrodes, the area of the x-axis or y-axis divided electrode is formed smaller, When the ratio of the displacement length of the center of gravity of the piezoelectric vibration sensor to the span of the split electrode for the axis or the y-axis increases, and the position of the center of gravity of the piezoelectric vibration sensor deviates from the center position of the piezoelectric body, The x-axis split electrode cannot cancel vibrations in the y-axis direction, and the y-axis split electrode cannot cancel vibrations in the x-axis direction, which is not preferable.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the piezoelectric vibration sensor of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, reference numeral 20 is a piezoelectric vibration sensor, and the piezoelectric vibration sensor 20 includes a pedestal 21 rigidly attached to an object to be measured, a sensor body 22 stacked on the pedestal 21, It is configured to have a spacer 23 stacked on the upper part of the sensor main body 22 and a load body 25 stacked on the upper surface of the spacer 23. The sensor body 22 is provided with a film-shaped piezoelectric body 26 for detecting the vibration of the pedestal 21, and a first substrate 27 and a second substrate 28 which are arranged on the front and back surfaces of the piezoelectric body 26 and sandwich the piezoelectric body 26. And the first substrate 27 and the piezoelectric body 2
6. The second substrate 28 has a three-layer structure.

The first substrate 27 is a substrate body made of a fiber reinforced resin (FRP) such as glass fiber reinforced epoxy resin in which epoxy resin is impregnated with glass fiber, and the entire front and back surfaces of the substrate body are plated with copper or the like. It is configured to have the first electrode 29 provided. Although the first electrode 29 is formed over the entire front and back surfaces of the substrate body, it may be provided over at least the entire surface facing the front surface (one surface) of the piezoelectric body 26.

The second substrate 28 is made of fiber reinforced resin (FR).
P), and a second electrode 31 provided on the entire surface of the substrate body 30 facing the back surface (the other surface) of the piezoelectric body 26 and provided on the front surface of the substrate body 30. There is. As shown in FIG. 2, the second electrode 31 is orthogonal to the back surface of the piezoelectric body 26 with the center of the back surface of the piezoelectric body 26 as an intersection, and a straight line passing through the intersection is defined as the z axis, and the z axis is Assuming that two perpendicular straight lines are the x-axis and the y-axis, respectively, one pair is arranged on the x-axis and the z
A pair of x-axis split electrodes 33 arranged point-symmetrically with respect to one point on the axis (substantially intersecting point), and a pair arranged on the y-axis, and point-symmetrical with respect to one point on the z-axis (substantially intersecting point). A pair of y arranged in
It is composed of an axis-divided electrode 34 and a z-axis electrode 35 whose center is located at the intersection.

That is, the z-axis electrode 35 is arranged in a square shape at the center of the back surface of the piezoelectric body 26.
The x-axis divided electrode 33 is arranged on the x-axis straddling, and the y-axis divided electrode 34 is arranged on the y-axis straddling the z-axis electrode 35. These x-axis split electrodes 33 and y-axis split electrodes 3
4 is formed in the substantially same rectangular shape,
They are arranged around the z-axis electrode 35 at equal intervals from the intersection. The x-axis split electrodes 33 are arranged in pairs on the x-axis, which are point-symmetric with respect to each other with the intersection point as a symmetry point. y
The pair of axis-divided electrodes 34 are arranged in pairs on the y-axis that is point-symmetrical with respect to the intersection. z-axis electrode 35
Is formed four times as large as one of the x-axis divided electrode 33 or the y-axis divided electrode 34. These x-axis split electrodes 33, y-axis split electrodes 34, z-axis electrodes 35
Are connected to electric wires (not shown) connected to the outside.

As the pedestal 21, a fiber reinforced resin (FR
A material made of a material having sufficient rigidity such as P) is preferable. As the film-shaped piezoelectric body 26, polyvinylidene fluoride,
Piezoelectric materials made of synthetic resin such as polyvinyl fluoride, copolymers of tetrafluoroethylene and trifluoroethylene,
A ceramic piezoelectric material having a perovskite structure such as a metal salt of titanate or a metal salt of zirconate can be used.

The spacer 23 is made of fiber reinforced resin (FRP).
Made of a material having sufficient rigidity such as, by separating the center of gravity of the load on the piezoelectric body 26 from the symmetrical point of the piezoelectric body 26,
Vibration components in the x-axis direction and the y-axis direction defined in the plane of the piezoelectric body 26 can be obtained with a high S / N ratio.
That is, the spacer 23 made of a material having a small specific gravity such as fiber reinforced resin constitutes a part of the load body 25, and the piezoelectric body 2
It is preferable that the load body 25 farther from 6 is made of a material having a large specific gravity such as brass.

The load body 25 has its center of gravity arranged on the z-axis passing through the intersection of the piezoelectric bodies 26, and is fixed to the upper surface of the spacer 23 with an adhesive or the like. By using a material having a large specific gravity such as tungsten or brass for the load body 25, the load body 25 can be downsized.

In such a piezoelectric vibration sensor, the pedestal 2
When the vibration is transmitted to 1, the piezoelectric body 26 is displaced, stress is generated in the piezoelectric body 26, and electric charges are generated on the surface of the piezoelectric body 26. By detecting the electric charge of the piezoelectric body 26 with the second electrode 31, the vibration in the three-dimensional directions of the x-axis, the y-axis, and the z-axis is detected. At this time, the vibration in the x-axis direction is detected by detecting the potential difference between the pair of x-axis divided electrodes 33, and the y-axis direction vibration is detected by detecting the potential difference between the pair of y-axis divided electrodes 34. Is detected, and by detecting the potential difference between the first electrode and the z-axis electrode 35, z
Axial vibration is detected.

According to such a piezoelectric type vibration sensor, the piezoelectric body 2 sandwiched between the first substrate 27 and the second substrate 28 is used.
6, a first electrode 29 provided over the entire front and back surfaces of the first substrate 27, and a second electrode 31 provided on the surface of the second substrate 28 facing the back surface of the piezoelectric body 26. Therefore, the first electrode 29 and the second electrode 31 are arranged on the front and back surfaces of the piezoelectric body 26. Therefore, the vibration is detected by detecting the potential difference between the first electrode 29 and the second electrode 31. Here, the second electrode 31 has a pair of x-axis divided electrodes 33 arranged on the x-axis, a pair of y-axis divided electrodes 34 arranged on the y-axis, and the center thereof is the piezoelectric body 26. Since the z-axis electrode 35 is located at the center of the z-axis, vibration in the z-axis direction is detected by detecting the potential difference between the first electrode 29 and the z-axis electrode 35. And
Since the first electrodes 29 are arranged to face each other over the entire surface of the piezoelectric body 26, vibration in the x-axis direction is detected by detecting the potential difference between the pair of x-axis divided electrodes 33.
The vibration in the y-axis direction is detected by detecting the potential difference between the pair of y-axis divided electrodes 34.

Split electrode 33 for x-axis and split electrode 34 for y-axis
Are formed in the same area and are arranged around the z-axis electrode 35 at equal intervals from the center of the piezoelectric body 26. The z-axis electrode 35 is the x-axis split electrode 33 or y.
Since the area is formed to be four times as large as that of one of the split electrodes 34 for the axis, the position of the center of gravity of the piezoelectric vibration sensor with respect to the span of the electrode 35 for the z axis when vibrating in the x-axis or y-axis direction. The proportion of the shift length is reduced, the proportion of the output detected by the z-axis electrode 35 is reduced, and the vibration detection accuracy in the z-axis direction can be improved. Therefore, even if the position of the center of gravity of the load body 25 in the z-axis direction deviates somewhat from the position of the center of gravity of the piezoelectric vibration sensor and vibrates in the x-axis direction or the y-axis direction, the vibration detection component in the z-axis direction. Is less. Therefore, even if the position of the center of gravity of the load body 25 deviates to some extent, the detection output in the z-axis direction can be reduced, so that when the load body 25 is fixed to the piezoelectric body 26, high positioning accuracy is achieved for the load body 25. Is unnecessary, and the workability in manufacturing the piezoelectric vibration sensor can be improved.

That is, in the manufacture of a piezoelectric vibration sensor, when the z axis is the main axis sensitivity, the ratio of the output appearing on the z axis when oscillating on the x and y axes (hereinafter referred to as crosstalk) is 5%. If the piezoelectric vibration sensor within the range is regarded as an acceptable product, the conventional vibration sensor provided with divided electrodes divided into nine equal parts and the piezoelectric vibration sensor of the present embodiment are respectively 3
Table 1 shows the result of producing 0 pieces.

[0026]

[Table 1]

The conventional pass rate (Comparative Example 1) is 40% (12
/ 30), the pass rate of this example (Example 1) was 90% (27/30). As is clear from the above results, the yield of the piezoelectric vibration sensor is improved. As shown in Table 1, in Comparative Example 2, when one of the x-axis divided electrode 33 or the y-axis divided electrode 34 is formed in an area 11 times larger than that of the z-axis electrode 35, the pass rate is increased. Is 20
% (2/10).

Although the piezoelectric body 26 is formed in a square shape in the above embodiment, the present invention is not limited to this.
It may be a regular polygon or a circle. It is preferable to arrange the position of the center of gravity of the load body 25 on the axis passing through the center of the regular polygonal or circular piezoelectric body 26. And the first substrate 2
Although the first electrode 29 is provided on 7 and the second electrode 31 is provided on the second substrate 28, the first electrode 29 and the second electrode may be provided directly on the piezoelectric body 26.

<Second Embodiment> A second embodiment of the piezoelectric vibration sensor of the present invention will be described with reference to FIG.
Here, the same parts as those in the above-mentioned embodiment are designated by the same reference numerals to simplify the description, and the same applies to each axial direction. The second embodiment and the first embodiment, as shown in FIG.
The arrangement of each electrode of 0 and the area ratio of each electrode are different. That is, a pair of the second electrodes 40 is arranged on the x-axis, and a pair of x is arranged point-symmetrically with respect to the intersection.
A pair of split electrodes 41 for the axis, a pair of split electrodes 42 for the y-axis that are arranged in a pair on the y-axis and are point-symmetrical with respect to the intersection, and the split electrode 41 for the x-axis and the split electrode 42 for the y-axis. And a z-axis electrode 43 arranged around the.

Split electrode 41 for x-axis and split electrode 42 for y-axis
Is formed in a square shape having the same area, and these corners are respectively positioned at the intersections, and the periphery of the intersections is divided into four equal parts. z-axis electrode 43
Is arranged at a position surrounding the x-axis divided electrode 41 and the y-axis divided electrode 42, and is formed in substantially the same area as one of the x-axis divided electrode 41 or the y-axis divided electrode 42. Has been done.

According to such a piezoelectric vibration sensor, a pair of the second electrodes 40 are arranged on the x-axis, and a pair of square-shaped divided electrodes 41 for the x-axis are arranged point-symmetrically with respect to the intersection.
And a pair of square-shaped split electrodes 42 for the y-axis, which are arranged in a pair on the y-axis and symmetrically with respect to the intersection, and around the split electrodes 41 for the x-axis and the split electrodes for the y-axis 42. Since the z-axis electrodes 43 are arranged, the vibration in the x-axis direction is detected by detecting the potential difference between the pair of x-axis split electrodes 41, and the potential difference between the pair of y-axis split electrodes 42 is detected. Is detected, the vibration in the y-axis direction is detected, and the vibration in the z-axis direction is detected by detecting the potential difference between the first electrode 29 and the z-axis electrode 43.

Split electrode 41 for x-axis and split electrode 42 for y-axis
Are formed in the same area and are arranged around the intersection, and the z-axis electrode 43 is the x-axis split electrode 4
Since one or one of the divided electrodes 42 for the y-axis is formed to have a single area, when vibrating in the x-axis or the y-axis direction,
The ratio of the length of displacement of the center of gravity of the piezoelectric vibration sensor to the z-axis electrode 43 having a large length is reduced, and x
The ratio of the length of the displacement of the center of gravity of the piezoelectric vibration sensor to the span of the split electrode 41 for the axis or the split electrode 42 for the y axis becomes small, and the ratio of the output detected by the z axis electrode 43 becomes low. Vibration detection accuracy in the axial direction can be improved. For this reason, even if the position of the center of gravity of the load body 25 in the z-axis direction deviates from the position of the center of gravity of the piezoelectric vibration sensor to some extent and vibrates in the x-axis direction or the y-axis direction, the detected component in the z-axis direction remains. Less. Therefore, even if the position of the center of gravity of the load body 25 deviates to some extent, the vibration detection output in the z-axis direction can be reduced, and therefore, when the load body 25 is fixed to the piezoelectric body 26, high positioning can be performed on the load body 25. No need for precision. Therefore, the vibration detection accuracy of the piezoelectric vibration sensor can be improved, the workability in manufacturing the piezoelectric vibration sensor can be improved, and the yield in manufacturing the piezoelectric vibration sensor can be improved.

That is, in the manufacture of the piezoelectric vibration sensor, assuming that the piezoelectric vibration sensor having a crosstalk of 5% or less is an acceptable product, the piezoelectric vibration sensor of the second embodiment is 10
The results of individual production are shown in Table 2.

[0034]

[Table 2]

The conventional pass rate (Comparative Example 1) is 40% (12
/ 30), the pass rate of the second example (Example 2) was 80% (8/10). As is clear from the above results, the yield of the piezoelectric vibration sensor is improved. As shown in Table 2, in Comparative Example 3, when the area of the z-axis electrode 43 was formed 2.6 times as large as one of the x-axis split electrode 41 or the y-axis split electrode 42, it passed. Rate is 30
% (3/10). In Comparative Example 4, when the area of the z-axis electrode 43 is 0.125 times larger than one of the x-axis split electrode 41 or the y-axis split electrode 42, the pass rate is 30% (3 / It was 10).

[0036]

As described above, according to the piezoelectric vibration sensor of the present invention, the following effects can be obtained.
The piezoelectric vibration sensor according to claim 1, wherein the piezoelectric vibration sensor has a structure in which a film-shaped piezoelectric body and a load body are laminated on a pedestal, and the piezoelectric body and the entire one surface of the piezoelectric body. The first electrode and the second electrode that are disposed on the other surface of the piezoelectric body and that detect a potential difference with respect to the first electrode are arranged. By detecting the potential difference between the two electrodes,
Vibration is detected.

A pair of second electrodes are arranged on the x-axis when two straight lines orthogonal to each other with the center of the other surface of the piezoelectric body as the intersection are defined as the x-axis and the y-axis. A pair of x-axis divided electrodes arranged point-symmetrically, a pair of y-axis divided electrodes arranged on the y-axis point-symmetrically with respect to the intersection, and the center thereof is located at the intersection. Since the z-axis electrode is formed, the vibration in the z-axis direction is detected by detecting the potential difference between the first electrode and the z-axis electrode. Since the first electrode is provided over the entire one surface of the piezoelectric body, the vibration in the x-axis direction is detected by detecting the potential difference between the pair of split electrodes for the x-axis, and the pair of y-axis split electrodes is detected. Vibration in the y-axis direction is detected by detecting the potential difference between the divided electrodes.

The x-axis split electrode and the y-axis split electrode are formed in the same area and are arranged around the z-axis electrode at equal intervals from the intersection, and the z-axis electrode is , For one of the x-axis or y-axis split electrodes, 1
Since the area is formed to be 10 times larger, the ratio of the length of displacement of the center of gravity of the piezoelectric vibration sensor to the span of the z-axis electrode is small when vibrating in the x-axis or y-axis direction. Therefore, the ratio of the output detected by the z-axis electrode is reduced, and the vibration detection accuracy in the z-axis direction can be improved.
Therefore, even if the position of the center of gravity of the load body in the z-axis direction deviates from the position of the center of gravity of the piezoelectric vibration sensor to some extent and vibrates in the x-axis direction or the y-axis direction, the detection component in the z-axis direction is small. Become. Therefore, the detection accuracy of the piezoelectric vibration sensor in the z-axis direction can be improved, and the vibration detection accuracy of the piezoelectric vibration sensor can be improved.

In addition, even if the position of the center of gravity of the load body deviates to some extent, the vibration detection output in the z-axis direction can be made small. Therefore, when the load body is fixed to the piezoelectric body, high positioning is possible with respect to the load body. No need for precision. Therefore, the workability of manufacturing the piezoelectric vibration sensor can be improved, and the yield in manufacturing the piezoelectric vibration sensor can be improved.

According to a second aspect of the piezoelectric vibration sensor, the piezoelectric vibration sensor has a structure in which a film-shaped piezoelectric body and a load body are laminated on a pedestal, and one of the piezoelectric body and the piezoelectric body is used. A first electrode distributed over the entire surface of
Since it is arranged on the other surface of the piezoelectric body and has a second electrode for detecting a potential difference with respect to the first electrode, the potential difference between the first electrode and the second electrode is detected. Thus, the vibration is detected. The second electrodes are arranged in a pair on the x-axis when two straight lines orthogonal to each other with the center of the other surface of the piezoelectric body as the intersection are taken as the x-axis and the y-axis, and are point-symmetrical with respect to the intersection. A pair of x-axis split electrodes arranged,
A pair of y-axis divided electrodes, which are arranged on the y-axis in a point symmetry with respect to the intersection, and these x-axis divided electrodes and y.
Since the z-axis electrodes are arranged around the axis-divided electrodes, the potential difference between the pair of x-axis divided electrodes, the potential difference between the pair of y-axis divided electrodes, and the first electrode and z The vibration in the three-dimensional direction is detected by detecting the potential difference with the shaft electrode.

The x-axis split electrode and the y-axis split electrode are formed in the same area and are arranged around the intersection, and the z-axis electrode is the x-axis or y-axis split electrode. Since it is configured to have an area of 0.125 to 2.5 times as large as one of the above, when it vibrates in the x-axis or y-axis direction, it is against the span of the split electrode for x-axis or y-axis. The ratio of the displacement length of the center of gravity of the piezoelectric vibration sensor becomes small, the ratio of the output detected by the z-axis electrode becomes low, and z
Vibration detection accuracy in the axial direction can be improved. For this reason,
Even if the position of the center of gravity of the load body in the z-axis direction deviates from the position of the center of gravity of the piezoelectric vibration sensor to some extent, and vibrates in the x-axis direction or the y-axis direction, the detection component in the z-axis direction decreases. Therefore, even if the position of the center of gravity of the load body deviates to some extent, the vibration detection output in the z-axis direction can be reduced, so that when the load body is fixed to the piezoelectric body, high positioning accuracy is unnecessary for the load body. Become. Therefore, the vibration detection accuracy of the piezoelectric vibration sensor can be improved, the workability in manufacturing the piezoelectric vibration sensor can be improved, and the yield in manufacturing the piezoelectric vibration sensor can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a developed state of a piezoelectric vibration sensor of the present invention.

2 is a front view showing the second electrode of FIG. 1. FIG.

FIG. 3 is a front view showing the second embodiment of FIG.

FIG. 4 is a perspective view showing a conventional piezoelectric vibration sensor.

FIG. 5 is a diagram showing a second example of a conventional piezoelectric vibration sensor, (a) showing a detection axis for vibration of a piezoelectric body, and (b).
FIG. 3 is a perspective view of a piezoelectric body.

6 is a circuit diagram showing an output voltage between each electrode of FIG.

FIG. 7 is a front view showing the piezoelectric body when the center of gravity of the load body is displaced.

[Explanation of symbols]

21 ... Pedestal, 25 ... Load body, 26 ... Piezoelectric body, 29 ... First electrode, 31.40 ... Second electrode, 33.41 ... X-axis split electrode, 34.42 ... Y-axis split electrode, 35 ・ 43 ...
Z-axis electrode.

Claims (2)

[Claims] 1. A piezoelectric vibration sensor having a structure in which a film-shaped piezoelectric body and a load body are laminated on a pedestal, wherein the piezoelectric body and a first electrode arranged on one entire surface of the piezoelectric body. And a second electrode disposed on the other surface of the piezoelectric body and detecting a potential difference with respect to the first electrode, the second electrode being the center of the other surface of the piezoelectric body. When two straight lines orthogonal to each other at the intersection are defined as the x-axis and the y-axis, a pair of split electrodes for the x-axis that are arranged in a pair on the x-axis and are symmetrical about the intersection, and on the y-axis A pair of divided electrodes for y-axis arranged symmetrically with respect to the intersection, and a z-axis electrode whose center is located at the intersection, and the divided electrode for x-axis. The y-axis split electrode is formed in the same area, and z-axis electrodes are formed at equal intervals from the intersection. The z-axis electrode is arranged around the pole, and the z-axis electrode is provided with respect to one of the x-axis or y-axis split electrodes
A piezoelectric vibration sensor having an area of 1 to 10 times. 2. A piezoelectric vibration sensor having a structure in which a film-shaped piezoelectric body and a load body are laminated on a pedestal, wherein the piezoelectric body and a first electrode arranged on one entire surface of the piezoelectric body. And a second electrode disposed on the other surface of the piezoelectric body and detecting a potential difference with respect to the first electrode, the second electrode being the center of the other surface of the piezoelectric body. When two straight lines orthogonal to each other at the intersection are defined as the x-axis and the y-axis, a pair of split electrodes for the x-axis that are arranged in a pair on the x-axis and are symmetrical about the intersection, and on the y-axis And a pair of y-axis divided electrodes that are arranged point-symmetrically with respect to the intersection, and z-axis electrodes that are arranged around the x-axis divided electrode and the y-axis divided electrode. The split electrode for x-axis and the split electrode for y-axis are formed in the same area, and And the z-axis electrode is arranged around one of the x-axis or y-axis split electrodes.
A piezoelectric vibration sensor having an area of 0.125 to 2.5 times.