JP2000065851A - Piezoelectric type three-axle acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric type three-axle acceleration sensor capable of setting optionally the magnitude of a Z-axis acceleration signal without using a signal amplification circuit. SOLUTION: In this acceleration sensor, board extension parts 13D, 13E extending to the outside of a base 5, and a diaphragm extension part 1b are installed on a piezoelectric ceramics board 9a and a diaphragm 1 respectively, and an additional deadweight 7 is installed on the outside end part on the back of the diaphragm extension part 1b. One-side electrodes DZ1, DZ3 between two pairs of Z-axis acceleration detection electrodes DZ1, DZ2 and DZ3, DZ4 are arranged adjacently to the base 5 and other-side electrodes DZ2, DZ4 are arranged adjacently to the additional deadweight 7. Each part of the piezoelectric ceramics board 9a corresponding to each electrode DZ1-DZ4 is polarized at the time when the same kind of stress is generated on each part, so that spontaneously-polarized charges having reverse polarities will be generated on the one-side electrodes DZ1, DZ3 and the other-side electrodes DZ2, DZ4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric type three-axis acceleration sensor for detecting three-axis accelerations in mutually orthogonal X-axis, Y-axis and Z-axis directions using piezoelectric ceramics. .

[0002]

2. Description of the Related Art FIG. 5 shows a basic electrode pattern formed on the surface of a piezoelectric ceramic substrate 101 used in a conventional piezoelectric type triaxial acceleration sensor. As shown in this figure,
On one surface of the piezoelectric ceramic substrate 101, a detection electrode pattern E101 is formed. The detection electrode pattern E101 includes an X-axis direction electrode pattern in which X-axis acceleration detection electrodes X1 and X2 and X-axis output electrodes X3 and X4 are connected in series by connection lines X5 and X6, respectively, and a Y-axis acceleration detection electrode pattern. The Y-axis direction electrode pattern in which the electrodes Y1, Y2 and the Y-axis output electrodes Y3, Y4 are connected in series by connection lines Y5, Y6, respectively, and the Z-axis acceleration detection electrodes Z1 to Z1 connected to each other by a connection line Z6. Z4 and Z-axis output electrode Z5
And the Z-axis direction electrode pattern connected by the connection line Z7. As shown in the schematic diagrams of FIGS. 6A and 6B, a counter electrode pattern E10 facing the acceleration detecting electrodes X1.
2 is formed. Also, the piezoelectric ceramic substrate 10
A diaphragm 102 is bonded to the back surface of the diaphragm 1 via an adhesive layer, and a columnar or cylindrical weight 103 is fixed to a central portion on the back surface side of the diaphragm.
A circular weight facing region 101A is formed in a portion of the piezoelectric ceramic substrate 101 facing the weight 103. Then, when the acceleration acts on the weight 103, the piezoelectric ceramic substrate 101 is mounted on the pedestal such that a stress generating region (intermediate region) 101B in which stress is generated outside the weight facing region 101A of the piezoelectric ceramic substrate 101 is formed. 104 is supported.

Each part of the piezoelectric ceramic substrate 101 corresponding to the X-axis acceleration detecting electrodes X1 and X2 has one X-axis acceleration detecting electrode X1 and the other X-axis acceleration detecting element when the same kind of stress is generated in each part. The polarization processing is performed in advance so that spontaneous polarization charges of opposite polarities appear on the acceleration detection electrode X2. Also, when the same type of stress is applied to each part of the piezoelectric ceramic substrate 101 corresponding to the Y-axis acceleration detection electrodes Y1 and Y2, one Y-axis acceleration detection electrode Y1 and the other Y-axis acceleration The polarization processing is performed in advance so that spontaneous polarization charges of opposite polarities appear on the detection electrode Y2. Further, each part of the piezoelectric ceramic substrate 101 corresponding to the four Z-axis acceleration detecting electrodes Z1 to Z4 has spontaneous polarization of the same polarity applied to all the Z-axis acceleration detecting electrodes when the same type of stress is generated in each part. A polarization process has been performed in advance so that charges appear.

In the conventional piezoelectric type triaxial acceleration sensor, the acceleration detecting electrodes X1, X2, Y1, Y2, and Z1 to Z4 form a weight facing region 101A on a surface of the piezoelectric ceramic substrate 101 corresponding to the stress generating region 101B. It is formed so as to form an annular row. Then, as shown in FIG. 6A, when an acceleration A1 in the X-axis direction acts on the weight 103, the piezoelectric ceramic substrate 101 deforms point-symmetrically about the center of gravity of the weight 103. In this case, a compressive stress is generated at the X-axis acceleration detecting electrode X1 and X
Tensile stress is generated at the axial acceleration detection electrode X2, and spontaneous polarization charges (positive in this case) having the same polarity appear on both the detection electrodes X1 and X2. X-axis output electrode X3
A current based on these same-polarity spontaneous polarization charges flows from X4. Similarly, when acceleration in the Y-axis direction is applied,
A current based on the charge obtained by adding the spontaneous polarization charges of the same polarity flows out from the shaft output electrodes Y3 and Y4.

On the other hand, as shown in FIG.
When the acceleration A2 in the Z-axis direction acts on the weight 103, a tensile stress is generated inside the portion of the piezoelectric ceramic substrate 101 on which the Z-axis acceleration detecting electrodes Z1, Z3,. Since the portions of the piezoelectric ceramic substrate corresponding to the Z-axis acceleration detecting electrodes Z1, Z3,... Are all polarized to the same polarity, all the Z-axis acceleration detecting electrodes Z1, Z3,. .. Appear in this case, and the charges appearing on the Z-axis acceleration detecting electrodes Z1, Z3,... Are added and output as a current signal or a voltage signal from the Z-axis output electrode Z5. In this way, the triaxial acceleration is detected by the current value or the voltage value output from each of the output electrodes X3, X4, Y3, Y4, and Z5.

However, in this type of piezoelectric triaxial acceleration sensor, as shown in FIG.
X-axis acceleration detecting electrodes X1 and X2 or Y-axis acceleration detecting electrode Y when axial acceleration acts on weight 103
6B, the stress concentrated on the Z-axis acceleration detecting electrodes Z1 when the same magnitude of acceleration acts on the weight 103 in the Z-axis direction as shown in FIG. Becomes smaller. Therefore, when detecting acceleration of the same magnitude, only the Z-axis acceleration signal (voltage or current) of the X-axis, Y-axis, and Z-axis acceleration signals obtained from the piezoelectric three-axis acceleration sensor is the other two. It is smaller than the acceleration signal. Therefore, conventionally, a signal amplifying circuit is provided in the sensor to match the magnitudes of the X-axis, Y-axis, and Z-axis acceleration signals.

[0007]

However, if a signal amplification circuit is provided in the sensor, the production of the piezoelectric triaxial acceleration sensor becomes complicated, and the miniaturization of the piezoelectric triaxial acceleration sensor is hindered. there were.

It is an object of the present invention to provide a piezoelectric type three-axis acceleration sensor which can arbitrarily set the magnitude of a Z-axis acceleration signal without using a signal amplification circuit.

Another object of the present invention is to provide a piezoelectric three-axis acceleration sensor which does not need to change the degree of amplification in accordance with acceleration signals in each direction even when an amplifier circuit is used, thereby simplifying the configuration and design of the amplifier circuit. Is to provide.

[0010]

SUMMARY OF THE INVENTION A piezoelectric three-axis acceleration sensor to which the present invention is applied is to detect three-axis accelerations in mutually orthogonal X-axis, Y-axis and Z-axis directions. A piezoelectric ceramic substrate having an X-axis acceleration detection electrode, a Y-axis acceleration detection electrode, and a Z-axis acceleration detection electrode on its front surface and having on its back surface a counter electrode facing each of the detection electrodes; The diaphragm to which the back surface of the piezoelectric ceramic substrate is joined, the weight provided at the center of the back surface of the diaphragm, and the portion of the piezoelectric ceramic substrate around the weight when acceleration acts on the weight. And a base for supporting the diaphragm. In the present invention, an X-axis acceleration detection electrode and a Y-axis acceleration detection signal are obtained so that an X-axis acceleration detection signal and a Y-axis acceleration detection signal are obtained by spontaneous polarization charges generated by bending of a portion of a piezoelectric ceramic substrate caused by displacement of a weight. Electrodes are arranged. The piezoelectric ceramic substrate and the diaphragm are provided with a substrate extension and a diaphragm extension respectively extending outside the base, and an additional weight is provided on the back surface of the diaphragm extension. Also, a Z-axis acceleration detecting electrode is arranged on the surface of the substrate extension so as to obtain a Z-axis acceleration detection signal by spontaneous polarization charges generated by bending of the substrate extension caused by displacement of the additional weight.

According to the piezoelectric type three-axis acceleration sensor of the present invention, in the area inside the base of the diaphragm (the center part of the piezoelectric ceramic substrate), the displacement of the weight causes the piezoelectric ceramic substrate to bend and the X-axis acceleration sensor to be bent. Spontaneous polarization charges appear on the detection electrode and the Y-axis acceleration detection electrode, and accelerations in the X-axis direction and the Y-axis direction are detected. In addition, in the region outside the base of the diaphragm (the substrate extension of the piezoelectric ceramic substrate), the extension of the substrate of the piezoelectric ceramic substrate bends due to the displacement of the additional weight, and spontaneous polarization charges appear on the Z-axis acceleration detection electrode, and Z An axial acceleration is detected. Therefore, in the substrate extension of the piezoelectric ceramic substrate,
The magnitude of the Z-axis acceleration signal can be arbitrarily set by changing the dimensions, shape, and weight of the Z-axis acceleration detection electrode, the additional weight, and the like. As a result, the magnitude of the Z-axis acceleration signal becomes X
The magnitudes of the axis acceleration signal and the Y axis acceleration signal can be the same. Therefore, it is possible to obtain a piezoelectric three-axis acceleration sensor that can match the output levels of acceleration signals using one diaphragm without using a signal amplification circuit. Further, since the signal levels of the X-axis acceleration signal, the Y-axis acceleration signal, and the Z-axis acceleration signal can be made the same, even if an amplifier circuit is used, it is not necessary to change the degree of amplification according to the acceleration signal in each direction. The circuit configuration and design are simplified.

The diaphragm, the weight, the base and the additional weight are preferably formed integrally. In this way, unlike the conventional acceleration detecting device in which each member is joined by an adhesive, the weight, the additional weight, and the base can be securely connected to the diaphragm. Further, since the weight and the additional weight are integrally formed with the diaphragm, the mounting position of the weight with respect to the diaphragm and the additional weight can be made constant, and a decrease in the measurement accuracy of the acceleration detection device can be suppressed. Also,
The number of parts of the acceleration detection device is reduced, and the manufacture of the acceleration detection device is facilitated.

The additional weight may be of various shapes. For example, a base having a cylindrical shape may be used, and the additional weight may have a cylindrical shape concentrically arranged with the base. in this case,
At least one pair of electrodes for Z-axis acceleration detection
The electrode for axis acceleration detection is arranged adjacent to the base, and the other electrode for Z axis acceleration detection is arranged adjacent to the additional weight.
Each portion of the substrate extension corresponding to one of the Z-axis acceleration detecting electrodes and the other Z-axis acceleration detecting electrode is polarized to have opposite polarities. With this configuration, when the acceleration in the Z-axis direction acts on the additional weight, the portion of the substrate extension corresponding to one Z-axis acceleration detection electrode and the substrate extension corresponding to the other Z-axis acceleration detection electrode Different types of stress are generated in the portion, and spontaneous polarization charges of the same polarity appear on one Z-axis acceleration detecting electrode and the other Z-axis acceleration detecting electrode. Thereby, the acceleration in the Z-axis direction is detected. When the acceleration in the X-axis direction or the Y-axis direction acts on the additional weight, the portions of the substrate extension corresponding to one Z-axis acceleration detection electrode and the other Z-axis acceleration detection electrode have the same type. Is generated, and spontaneously polarized charges of opposite polarity appear on one Z-axis acceleration detecting electrode and the other Z-axis acceleration detecting electrode. As a result, the spontaneously polarized charges generated in the Z-axis acceleration detection electrode cancel each other, and the acceleration component in the X-axis direction or the Y-axis direction is canceled.

Further, the substrate extension portion is constituted by one or more pairs of substrate extension piece segments arranged at intervals of 180 degrees in the circumferential direction, and the diaphragm extension portion is constituted by a pair of substrate extension segments. It is also possible to form a pair of supporting diaphragm extension segments, and to provide a pair of Z-axis acceleration detecting electrodes on each of the pair of substrate extension pieces. In this case, one additional weight is provided for each of the pair of diaphragm extension segments, and the portions of the piezoelectric ceramic substrate corresponding to the Z-axis acceleration detecting electrodes are polarized to have the same polarity. In this way, when the acceleration in the Z-axis direction acts on the additional weight,
The same type of stress is generated in each part of the piezoelectric ceramic substrate corresponding to each Z-axis acceleration detecting electrode, and spontaneous polarization charges of the same polarity appear on the Z-axis acceleration detecting electrode. If two pairs of Z-axis acceleration detecting electrodes are connected in common, acceleration in the Z-axis direction is detected. Further, when the acceleration in the X-axis direction or the Y-axis direction acts on the additional weight, a portion of the substrate extension piece segment corresponding to one of the paired Z-axis acceleration detection electrodes and the other Z-axis acceleration detection electrode are paired. A different type of stress is generated in the portion of the substrate extension piece segment corresponding to the axis acceleration detection electrode, and spontaneous polarization of opposite polarity is applied to one Z-axis acceleration detection electrode and the other Z-axis acceleration detection electrode. A charge appears. If two pairs of Z-axis acceleration detecting electrodes are commonly connected, the spontaneously polarized charges generated in the Z-axis acceleration detecting electrodes cancel each other out, and the acceleration component in the X-axis direction or the Y-axis direction is canceled.

A piezoelectric three-axis acceleration sensor having a more specific structure according to the present invention comprises a pair of X-axis sensors for detecting three-axis accelerations in an X-axis direction, a Y-axis direction, and a Z-axis direction which are orthogonal to each other. A piezoelectric ceramic substrate having an acceleration detection electrode, a pair of Y-axis acceleration detection electrodes, and a pair of or more Z-axis acceleration detection electrodes on the front surface and one or more counter electrodes on the back surface facing the detection electrodes. And a diaphragm having a front surface joined to the back surface of the piezoelectric ceramic substrate, a weight provided at the center of the back surface of the diaphragm, and a portion of the piezoelectric ceramic substrate around the weight when acceleration acts on the weight. And a cylindrical base for supporting the diaphragm so that the diaphragm is bent. Then, a pair of X-axis acceleration detecting electrodes are arranged side by side in the X-axis direction with a weight therebetween, and the portions of the piezoelectric ceramic substrate corresponding to the pair of X-axis acceleration detecting electrodes are respectively polarized to opposite polarities, A pair of Y
The electrodes for axial acceleration detection are arranged side by side in the Y-axis direction with a weight in between, and the portions of the piezoelectric ceramic substrate corresponding to the pair of electrodes for Y-axis acceleration detection are polarized to have opposite polarities. Then, the piezoelectric ceramic substrate and the diaphragm are provided with a substrate extension and a diaphragm extension respectively extending outside the base, and at the outer end of the back surface of the diaphragm extension, a cylindrical additional weight is provided concentrically with the base, A pair of Z
One of the Z-axis acceleration detecting electrodes is disposed adjacent to the base, and the other Z-axis acceleration detecting electrode is disposed adjacent to the additional weight. The portions of the substrate extension corresponding to the one Z-axis acceleration detecting electrode and the other Z-axis acceleration detecting electrode are polarized in opposite polarities.

More specifically, one Z-axis acceleration detecting electrode is formed so as to enter a region facing the base of the piezoelectric ceramic substrate, and the other Z-axis acceleration detecting electrode is formed by adding a substrate extension. What is necessary is just to form so that it may straddle the area | region which opposes a weight and the area | region which does not oppose an additional weight.

Another piezoelectric three-axis acceleration sensor having a more specific structure of the present invention is a pair of piezoelectric three-axis acceleration sensors for detecting three-axis accelerations in mutually orthogonal X-axis, Y-axis, and Z-axis directions. A piezoelectric element having an X-axis acceleration detection electrode, a pair of Y-axis acceleration detection electrodes, and two pairs of Z-axis acceleration detection electrodes on its front surface and one or more counter electrodes on its back surface facing each of the detection electrodes. A ceramic substrate, a diaphragm having a front surface joined to the back surface of the piezoelectric ceramic substrate, a weight provided at the center of the back surface of the diaphragm, and a piezoelectric ceramic around the weight when acceleration acts on the weight. A cylindrical base for supporting the diaphragm so that a portion of the substrate is bent. And a pair of X
The electrodes for axis acceleration detection are arranged side by side in the X-axis direction with a weight therebetween, and the portions of the piezoelectric ceramic substrate corresponding to the pair of electrodes for X-axis acceleration detection are polarized to opposite polarities, respectively. The detection electrodes are arranged side by side in the Y-axis direction with a weight therebetween, and the portions of the piezoelectric ceramic substrate corresponding to the pair of Y-axis acceleration detection electrodes are respectively polarized in opposite polarities. The piezoelectric ceramic substrate and the diaphragm are provided with a substrate extension and a diaphragm extension respectively extending outside the base, and the substrate extension is provided with a pair of substrate extension piece segments extending outward in the X-axis direction and a pair of substrate extension segments extending outward in the Y-axis direction. It is composed of a substrate extension piece segment. In addition, the diaphragm extension portion is constituted by two pairs of diaphragm extension segments that support two pairs of substrate extension segments, one Z-axis acceleration detection electrode is provided on each of the substrate extension piece segments, and a plurality of diaphragm extension segments are provided. , One additional weight is provided. Then, the portions of the substrate extension piece segments corresponding to all the Z-axis acceleration detecting electrodes are polarized to have the same polarity.

More specifically, the Z-axis acceleration detecting electrode is preferably formed so as to straddle a region of the substrate extension piece segment facing the weight and a region not facing the weight.

Also, like the X-axis acceleration detection electrode and the Y-axis acceleration detection electrode, a part of the plurality of Z-axis acceleration detection electrodes may be deformed by the deflection of the piezoelectric ceramic substrate caused by the displacement of the weight. Is arranged so as to obtain a part of the Z-axis acceleration detection signal, and the remaining electrodes of the plurality of Z-axis acceleration detection electrodes are replaced with the remaining Z-axis acceleration detection signal due to the bending of the substrate extension caused by the displacement of the additional weight. It may be arranged so as to obtain.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a schematic plan view of a piezoelectric triaxial acceleration sensor according to one embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line BB of FIG. 1A. As shown in both figures, this piezoelectric three-axis acceleration sensor includes a diaphragm 1, a weight 3, a base 5, an additional weight 7, and an acceleration detecting element 9. In this figure, the thickness of each part of the acceleration detecting element 9 is exaggerated for easy understanding.

The diaphragm 1, the weight 3, the base 5 and the additional weight 7 are integrally formed of a metal material made of brass. The diaphragm 1 has a disk shape,
It has a thickness of 0.1 mm. This diaphragm 1
Has a disk-shaped diaphragm main body 1a located inside the base 5, and an annular diaphragm extension 1b extending outside the base 5 and surrounding the diaphragm main body 1a. The weight 3 has a columnar shape, and is provided at the center of the rear surface of the diaphragm 1 so that the extension of the axis passes through the center of the diaphragm 1. The base 5 has a cylindrical shape surrounding the weight 3, and supports the diaphragm 1 so that when acceleration is applied to the weight 3, a portion of the diaphragm 1 around the weight 3 is bent. .
By joining the base 5 to the mounting member 11,
The piezoelectric triaxial acceleration sensor is fixed to the mounting member 11. The additional weight 7 has a cylindrical shape, and is provided concentrically with the base 5 at the outer end on the back surface of the diaphragm extension 1b. In this embodiment, a cylindrical metal material made of brass was prepared, and the cylindrical metal material was subjected to cutting to integrally form the diaphragm 1, the weight 3, the base 5, and the additional weight 7.

The acceleration detecting element 9 is configured such that a triaxial acceleration detecting electrode pattern E1 is formed on the surface of a piezoelectric ceramic substrate 9a, and a counter electrode pattern E2 is formed on the back surface. In this example, the back surface of the piezoelectric ceramic substrate 9a and the counter electrode pattern E2 are joined to the surface of the diaphragm 1 by an epoxy-based adhesive, and the acceleration detecting element 9 is attached to the diaphragm 1. The piezoelectric ceramic substrate 9a has a disk shape, and a polarization process is performed on a portion corresponding to the acceleration detection electrodes DX1 so that a spontaneous polarization charge is generated when stress is applied to the inside. The polarization process will be described later in detail.

The piezoelectric ceramic substrate 9a includes a weight facing region 13A, an inner stress generating region 13B, and a base facing region 1A.
3C, outer stress generating area 13D, and additional weight facing area 13
E. The weight facing region 13 </ b> A has a circular shape at the center of the piezoelectric ceramic substrate 1. The weight 3 is located in a portion corresponding to the weight facing region 13A.

The inner stress generating region 13B has an annular shape surrounding the weight facing region 13A. The inner peripheral side portion (radially inner side portion) of the first stress generation region 13B is
When acceleration is applied to the weight 3 in a direction parallel to the piezoelectric ceramic substrate 9a, different states are point-symmetrically centered on the center of gravity of the weight 3 (a state where a tensile stress is applied and a state where a compressive stress is applied). ). When acceleration acts on the weight 3 in a direction orthogonal to the piezoelectric ceramic substrate 9a, each part of the inner peripheral side portion of the first stress generation region 13B is deformed to the same state. When an acceleration acts on the weight 3 in a direction orthogonal to the piezoelectric ceramic substrate 1, the outer peripheral side portion (radially outer portion) of the first stress generation region 13 </ b> B Deforms to a state different from the inner peripheral part.

The base facing region 13C has an annular shape surrounding the first stress generating region 13B. The base 5 is located at a portion corresponding to the base facing region 13C.

The outer stress generating region 13D has an annular shape surrounding the base facing region 13C. When an acceleration acts on the additional weight 7 in a direction parallel to the piezoelectric ceramic substrate 9a (X-axis direction, Y-axis direction), the inner peripheral portion (radial inner portion) of the outer stress generating region 13D becomes Is deformed in either a state where a tensile stress is applied or a state where a compressive stress is applied. On the other hand, when acceleration acts on the additional weight 7 in a direction perpendicular to the piezoelectric ceramic substrate 9a, the outer stress generation region 1
Each portion of the inner peripheral side portion (the portion close to the base 5) of the 3D is deformed in the same state, and the outer peripheral side portion (the portion close to the additional weight 7) of the outer stress generating region 13D is
It deforms in a state different from the inner peripheral portion of D.

The additional weight facing region 13E has an annular shape surrounding the outer stress generating region 13D. The additional weight 7 is located at a portion corresponding to the additional weight facing region 13E. The outer stress generating region 13D and the additional weight facing region 13E correspond to the diaphragm extension 1b of the diaphragm 1. In this example, the outer stress generating region 13D and the additional weight facing region 13E form the piezoelectric ceramic substrate. A substrate extension 9a is formed.

The detection electrode pattern E1 and the counter electrode pattern E2 formed on the front and back surfaces of the piezoelectric ceramic substrate 9a are both formed by screen printing. The counter electrode pattern E2 is the acceleration detection electrodes DX1, DX2, D of the detection electrode pattern E1 described later.
Y1, DY2, DZ1 and DZ4 are formed at portions opposed to each other. When the diaphragm 1 is deformed based on the acceleration acting on the weight 3 or the additional weight 7, the spontaneous polarization charge generated between the acceleration detection electrode DX1 of the detection electrode pattern E1 and the counter electrode pattern E2 changes. Then, accelerations in three axes (X axis, Y axis, Z axis) are measured as changes in current or voltage. Note that X here
The axis, the Y axis, and the Z axis are axes extending in directions orthogonal to each other, the X axis extends in the direction of a virtual straight line XL, the Y axis extends in the direction of a virtual straight line YL, and the Z axis is a piezoelectric ceramic substrate. 9a extends in a direction orthogonal to the plane direction.

The detection electrode pattern E1 is composed of an X-axis electrode pattern 15, a Y-axis electrode pattern 17, and a Z-axis electrode pattern 19.
And The X-axis electrode pattern 15 has a structure in which a pair of X-axis acceleration detection electrodes DX1 and DX2 and the X-axis output electrode OX are connected by a connection line L1. The X-axis acceleration detecting electrodes DX1 and DX2 are arranged side by side with the weight 3 in the direction of the virtual straight line XL. Also, X
Most of the axial acceleration detecting electrodes DX1 and DX2 are
Is formed so as to be located on a surface corresponding to the inner peripheral side portion (radially inner side portion) of the stress generation region 13B of FIG.
An edge portion along the inner periphery of the first stress generation region 13B enters the weight facing region 13A. The X-axis output electrode OX has a rectangular shape and is formed so as to be located on the base facing region 13C.

The Y-axis electrode pattern 17 has a structure in which a pair of Y-axis acceleration detecting electrodes DY1 and DY2 and a Y-axis output electrode OY are connected by connection lines L2 and L3. Y
The axial acceleration detecting electrodes DY1 and DY2 are arranged side by side with the weight 3 in the virtual straight line YL direction. The Y-axis acceleration detection electrodes DY1 and DY2 also have the same shape as the X-axis acceleration detection electrodes DX1 and DX2, and most of the Y-axis acceleration detection electrodes DX1 and DX2 are located on the inner peripheral side of the first stress generation region 13B (the radially inner portion ) Is formed on the surface corresponding to
An edge portion along the inner circumference of the first stress generation region 5B enters the weight facing region 13A. Since the virtual Y-axis straight line YL and the virtual X-axis straight line XL are orthogonal to each other, the X-axis acceleration detection electrode DX1, the Y-axis acceleration detection electrode DY1, the X-axis acceleration detection electrode DX2, and the Y-axis acceleration detection electrode DY2
Are arranged at intervals of 90 degrees. The Y-axis output electrode OY has a rectangular shape like the X-axis output electrode OX, and is formed so as to be located on the base facing region 13C.

Each portion of the piezoelectric ceramic substrate 9a corresponding to the X-axis acceleration detecting electrodes DX1 and DX2 has an X-position which is located on one side when the same type of stress is generated in each portion.
The polarization processing is performed so that spontaneous polarization charges of opposite polarities appear on the axial acceleration detecting electrode DX1 and the X-axis acceleration detecting electrode DX2 located on the other side, respectively. In this example, when a tensile stress is generated in each part of the piezoelectric ceramic substrate 9a corresponding to the X-axis acceleration detection electrodes DX1 and DX2, a positive spontaneous polarization charge appears on the X-axis acceleration detection electrode DX1, and The polarization processing is performed so that a negative spontaneous polarization charge appears on the acceleration detection electrode DX2.

Further, the Y-axis acceleration detecting electrodes DY1, DY
Each of the portions of the piezoelectric ceramic substrate 9a corresponding to the electrode 2 is also similar to the respective portions of the piezoelectric ceramic substrate 9a corresponding to the X-axis acceleration detecting electrodes DX1 and DX2 when one of the same types of stress is generated in each portion. Are polarized so that spontaneously polarized charges of opposite polarities appear on the Y-axis acceleration detecting electrode DY1 located on the other side and the Y-axis acceleration detecting electrode DY2 located on the other side. In this example, when a tensile stress is generated in each part of the piezoelectric ceramic substrate 9a corresponding to the Y-axis acceleration detecting electrodes DY1 and DY2, Y
The polarization processing was performed so that a positive spontaneous polarization charge appeared on the axis acceleration detection electrode DY1 and a negative spontaneous polarization charge appeared on the Y-axis acceleration detection electrode DY2. These polarization processes are performed by the detection electrode pattern E1 and the counter electrode pattern E1.
This was performed by applying a DC voltage to the piezoelectric ceramics substrate 9a at a stage before forming the connection lines L1 to L6 after forming 2.

The Z-axis electrode pattern 19 includes a pair of Z-axis acceleration detecting electrodes DZ1, DZ connected by a connection line L4.
2, a pair of Z-axis acceleration detecting electrodes DZ3 and DZ4 connected by a connection line L5, and a Z-axis output electrode OZ are connected by a connection line L6. Two pairs of electrodes for Z-axis acceleration detection (DZ1, DZ2) and (DZ3, DZ3
Z4), one of the electrodes DZ1 for Z-axis acceleration detection
And DZ3 are arranged adjacent to the base 5, and the other Z-axis acceleration detecting electrodes DZ2 and DZ4 are arranged adjacent to the additional weight 7. More specifically, one of the Z-axis acceleration detection electrodes DZ1 and DZ3 is
Most of the outer stress generating region 13D is formed so as to be located on a surface corresponding to an inner peripheral side portion (radially inner portion) of the outer stress generating region 13D, and an edge portion along the inner periphery of the outer stress generating region 13D faces the base. It has entered the area 13C. The other Z-axis acceleration detection electrodes DZ2 and DZ4 are formed so that most of them are located on a surface corresponding to the outer peripheral side portion (radially outer portion) of the outer stress generating region 13D.
An edge portion along the outer periphery of the outer stress generation region 13D enters the additional weight facing region 13E. Z-axis output electrode OZ
Has a rectangular shape like the X-axis output electrode OX,
It is formed so as to be located on the base facing region 13C. In this example, the X-axis acceleration detection electrodes DX1, DX2,
After forming the Y-axis acceleration detecting electrodes DY1 and DY2 and the Z-axis acceleration detecting electrodes DZ1 to DZ4 by screen printing using silver paste to a thickness of 10 μm, the connection line L1 is formed.
To L6 were formed by screen printing using a silver paste to form a detection electrode pattern E1.

One Z-axis acceleration detecting electrodes DZ1 and DZ
Z3 and the other Z-axis acceleration detecting electrodes DZ2 and DZ
Each of the portions of the piezoelectric ceramic substrate 9a corresponding to No. 4 has one Z-axis acceleration detecting electrodes DZ1 and DZ3 and the other Z-axis acceleration detecting electrodes DZ2 and DZ4 when the same type of stress is generated in each portion. Are polarized such that spontaneous polarization charges of opposite polarities appear. In this example, Z
When tensile stress is generated in each part of the piezoelectric ceramic substrate 9a corresponding to the axial acceleration detecting electrodes DZ1 to DZ4, a negative spontaneous polarization charge appears on one of the Z-axis acceleration detecting electrodes DZ1 and DZ3, and the other Z The polarization processing is performed so that a positive spontaneous polarization charge appears on the axial acceleration detection electrodes DZ2 and DZ4. In other words, when a compressive stress is generated in each part of the substrate extension of the piezoelectric ceramic substrate 9a corresponding to the Z-axis acceleration detecting electrodes DZ1 to DZ4, one of the Z-axis acceleration detecting electrodes DZ
1 and DZ3 show a positive spontaneous polarization charge and the other Z
Polarization processing is performed so that negative spontaneous polarization charges appear on the axial acceleration detection electrodes DZ2 and DZ4. Further, in this example, when an acceleration of a certain magnitude acts in the Z-axis direction, a combined output (Z-axis acceleration detection signal) obtained from the Z-axis acceleration detection electrodes DZ1 to DZ4 is an acceleration of the same magnitude as the acceleration. A combined output (X-axis acceleration detection signal) obtained from the X-axis acceleration detection electrodes DX1 and DX2 when acting in the X-axis direction or the Y-axis direction, or a composite output obtained from the Y-axis acceleration detection electrodes DY1 and DY2. The dimensions and shape of the Z-axis acceleration detection electrodes DZ1 to DZ4 and the additional weight 7 are designed to be substantially equal to (Y-axis acceleration detection signal).

In the piezoelectric type triaxial acceleration sensor of this embodiment, FIG.
As shown in the schematic diagram of (A), when the acceleration A3 in the Z-axis direction acts on the additional weight 7, the piezoelectric ceramic substrate 9a corresponding to one of the Z-axis acceleration detection electrodes DZ1 and DZ3.
Compressive stress is generated in each portion of the substrate extension portion, and a positive spontaneous polarization charge appears in the Z-axis acceleration detection electrodes DZ1 and DZ3. Also, the other Z-axis acceleration detecting electrode D
Tensile stress is generated in each portion of the substrate extension portion of the piezoelectric ceramic substrate 9a corresponding to Z2 and DZ4, and positive spontaneous polarization charges also appear on the Z-axis acceleration detection electrodes DZ2 and DZ4. Thereby, the acceleration in the Z-axis direction is detected.

Also, as shown in the schematic diagram of FIG.
When the acceleration A4 in the Y-axis direction acts on the additional weight 7, the piezoelectric ceramic substrate 9a corresponding to one of the Z-axis acceleration detecting electrodes DZ1 and the other Z-axis acceleration detecting electrode DZ2 has a portion extending from the substrate. , Compressive stress is generated, and one Z
A positive spontaneous polarization charge appears on the axial acceleration detection electrode DZ1, and a negative spontaneous polarization charge appears on the other Z-axis acceleration detection electrode DZ2. Further, a tensile stress is generated in each portion of the substrate extension portion of the piezoelectric ceramic substrate 9a corresponding to one of the Z-axis acceleration detecting electrodes DZ3 and the other Z-axis acceleration detecting electrode DZ4, and one of the Z-axis acceleration detecting electrodes DZ3 is detected. A negative spontaneous polarization charge appears on the electrode DZ3, and a positive spontaneous polarization charge appears on the other Z-axis acceleration detection electrode DZ4. Therefore, when the acceleration in the Y-axis direction is generated, the spontaneously polarized charges generated in the Z-axis acceleration detection electrodes DZ1 to DZ4 cancel each other out, and a signal indicating that the acceleration is acting in the Z-axis direction is erroneous. Will not be output. Also, with respect to the generation of the acceleration in the X-axis direction, a signal indicating that the acceleration is acting in the Z-axis direction as in the Y-axis direction is not erroneously output.

In this example, the substrate extension (13D, 1
3E) Z-axis acceleration detecting electrodes DZ1-D
Z4 is arranged. However, apart from these Z-axis acceleration detecting electrodes DZ1 to DZ4, a part of the plurality of Z-axis acceleration detecting electrodes (electrodes indicated by reference symbol DZ5) is separated from the piezoelectric ceramic substrate 39a by the weight 3 ( (The portion where the X-axis acceleration detecting electrode and the Y-axis acceleration detecting electrode are disposed). In this case, the sum of the outputs of the Z-axis acceleration detection electrodes DZ1 to DZ4 and the outputs of the Z-axis acceleration detection electrodes DZ5... Becomes a Z-axis acceleration detection signal.

FIG. 3A is a schematic plan view of a piezoelectric three-axis acceleration sensor according to another embodiment of the present invention.
FIG. 3B is a sectional view taken along line BB of FIG. The structure of the piezoelectric three-axis acceleration sensor of the present embodiment is different from the structure of the piezoelectric three-axis acceleration sensor shown in FIGS. In this example, a pair of substantially rectangular substrate extension piece segments 21X, 21Y... Extending outward in the X-axis direction and outward in the Y-axis direction constitute a substrate extension portion of the piezoelectric ceramic substrate 39a. That is,
A pair of substrate extension piece segments 21X, 21X each extending in the X-axis direction are arranged at an interval of 180 degrees, and a pair of substrate extension piece segments 21Y, 21Y respectively extending in the Y-axis direction form an angle of 180 degrees. Are arranged at intervals. The diaphragm extension portion 31b of the diaphragm 31 is constituted by two pairs of diaphragm extension segments 23 that support two pairs of substrate extension segments 21X, 21Y. Each of the diaphragm extension segments 23 has a substantially rectangular shape like the substrate extension piece segments 21. Therefore, the diaphragm 31 has a shape in which four rectangular segments project from the disk.

Each of the additional weights 37 is provided for each of the four diaphragm extension segments 23. The additional weight 37 has a cylindrical shape, and is integrally formed of a metal material made of the diaphragm 31, the weight 3, the base 5 and brass.

The Z-axis electrode pattern 49 has four Z-axis electrode patterns.
It has a structure in which the axis acceleration detection electrodes DZ1 'to DZ4' and the Z-axis output electrode OZ 'are connected by a connection line L7. Each of the Z-axis acceleration detecting electrodes DZ1 ′ to DZ4 ′ is provided one by one in correspondence with the board extension piece segments 21. More specifically, the Z-axis acceleration detection electrodes DZ1 'to DZ4' are mainly areas (not between the additional weight 37 and the base 5) 43D of the board extension piece segments 21X and 21Y that do not face the additional weight 37. And a part thereof enters the region 43 </ b> E facing the additional weight 37. Each Z-axis output electrode OZ 'has a rectangular shape and is formed so as to be located on the base facing region 43C. Also, the counter electrode pattern E
12 is an acceleration detection electrode DX of the detection electrode pattern E11.
1, DX2, DY1, DY2, DZ1 'to DZ4'.

Z-axis acceleration detecting electrodes DZ1 'to DZ4'
Are respectively polarized so that spontaneous polarization charges of the same polarity appear on each electrode when the same type of stress is generated. In this example, when tensile stress is generated in each of the board extension piece segments 21X and 21Y corresponding to the Z-axis acceleration detection electrodes DZ1 'to DZ4', the Z-axis acceleration detection electrodes DZ1 'to DZ4 are generated.
The polarization process is performed so that a negative spontaneous polarization charge appears at 4 '. In other words, when compressive stress is generated in each of the board extension piece segments 21X and 21Y corresponding to the Z-axis acceleration detection electrodes DZ1 'to DZ4', the Z-axis acceleration detection electrodes DZ1 'to DZ4 are generated. 'Has been subjected to a polarization treatment so that a positive spontaneous polarization charge appears. Also in this example, when acceleration of a certain magnitude acts in the Z-axis direction, the Z-axis acceleration detecting electrodes DZ1 'to DZ1
When the combined output based on the spontaneous polarization charge appearing in Z4 'is applied with the same magnitude of acceleration in the X-axis direction or the Y-axis direction, the X-axis acceleration detection electrodes DX1, DX2 and the Y-axis acceleration detection electrodes DY1, DY2 Z is set to be substantially equal to each output obtained based on the spontaneous polarization charge appearing at
Axial acceleration detecting electrodes DZ1 'to DZ4' and additional weight 3
The dimensions and shape of 7 are designed.

In the piezoelectric type triaxial acceleration sensor of this embodiment, FIG.
As shown in the schematic diagram of (A), when the acceleration A5 in the Z-axis direction acts on the additional weight 37, the Z-axis acceleration detection electrode DZ
Board extension piece segment 21 corresponding to 2 ', DZ4'
In Y and 21Y, compressive stress is generated over the entire region, and positive spontaneous polarization charges appear on the Z-axis acceleration detecting electrodes DZ2 ′ and DZ4 ′. At this time, the board extension piece segment 2 corresponding to the Z-axis acceleration detection electrodes DZ1 'and DZ3'
Compressive stress is also generated in each of the portions 1X and 21X, and positive spontaneous polarization charges also appear in the Z-axis acceleration detecting electrodes DZ1 'and DZ3'. Thereby, the acceleration in the Z-axis direction is detected.

As shown in the schematic diagram of FIG.
When the acceleration A6 in the Y-axis direction acts on the additional weight 37, Z
Compressive stress is generated in a portion of the one substrate extension piece segment 21Y corresponding to the axial acceleration detection electrode DZ2 ', and Z
A positive spontaneous polarization charge appears on the axial acceleration detection electrode DZ2 '. Further, a tensile stress is generated in a portion of the other substrate extension piece segment 21Y corresponding to the Z-axis acceleration detection electrode DZ4 ', and a negative spontaneous polarization charge appears in the Z-axis acceleration detection electrode DZ4'. Therefore, the spontaneously polarized charges generated in the Z-axis acceleration detection electrodes DZ2 'and DZ4' cancel each other out. Further, only a twisting stress is generated in both of the board extension piece segments 21X, 21X, and no output is produced from the Z-axis acceleration detecting electrodes DZ1 ', DZ3'. Therefore, a signal indicating that the acceleration in the Z-axis direction is acting when the acceleration in the Y-axis direction acts is not erroneously output. Also, when the acceleration in the X-axis direction is applied, a signal indicating that the acceleration in the Z-axis direction is applied is not erroneously output for the same reason.

In this example, the substrate extension portions (43D, 4D)
3E) Z-axis acceleration detecting electrodes DZ1 ′ to
DZ4 'is arranged. However, some of the plurality of electrodes for Z-axis acceleration detection (electrodes indicated by reference symbol DZ5 ') are
Apart from these Z-axis acceleration detecting electrodes DZ1 'to DZ4', a piezoelectric ceramic substrate 39 displaced by the weight 3 is provided.
It may be arranged at the part a (the part where the X-axis acceleration detecting electrode and the Y-axis acceleration detecting electrode are arranged). In this case, the Z-axis acceleration detecting electrodes DZ1 'to DZ1
4 ′ and the output of the Z-axis acceleration detection electrodes DZ5 ′... Become the Z-axis acceleration detection signal.

[0045]

According to the present invention, in the region inside the base of the diaphragm (the center portion of the piezoelectric ceramic substrate), the piezoelectric ceramic substrate is bent by the displacement of the weight and X
Spontaneous polarization charges appear on the axis acceleration detecting electrode and the Y axis acceleration detecting electrode, and the accelerations in the X axis direction and the Y axis direction are detected. In addition, in the region outside the base of the diaphragm (the substrate extension of the piezoelectric ceramic substrate), the extension of the substrate of the piezoelectric ceramic substrate bends due to the displacement of the additional weight, and spontaneous polarization charges appear on the Z-axis acceleration detection electrode, and Z An axial acceleration is detected. Therefore, the magnitude of the Z-axis acceleration signal can be arbitrarily set by changing the size, shape, and weight of the Z-axis acceleration detection electrode, the additional weight, and the like in the substrate extension portion of the piezoelectric ceramic substrate. As a result, the magnitude of the Z-axis acceleration signal can be made equal to the magnitude of the X-axis acceleration signal and the magnitude of the Y-axis acceleration signal. Therefore, using one diaphragm, without using a signal amplification circuit,
A piezoelectric three-axis acceleration sensor that can match the output levels of the acceleration signals can be obtained. Further, since the signal levels of the X-axis acceleration signal, the Y-axis acceleration signal, and the Z-axis acceleration signal can be made equal, even if an amplifier circuit is used,
Since it is not necessary to change the degree of amplification according to the acceleration signal in each direction, the configuration and design of the amplifier circuit are simplified.

[Brief description of the drawings]

FIG. 1A is a schematic plan view of a piezoelectric three-axis acceleration sensor according to one embodiment of the present invention, and FIG.
It is a BB sectional view taken on the line of (A).

FIG. 2A is a diagram illustrating the spontaneous polarization charge of the Z-axis acceleration detecting electrode when acceleration in the Z-axis direction acts on an additional weight in the piezoelectric triaxial acceleration sensor of the embodiment shown in FIG. It is a figure used for description, and (B) is a mimetic diagram used for explaining spontaneous polarization charge of the electrode for Z-axis acceleration detection when acceleration in the direction of the Y-axis acts on an additional weight.

3A is a schematic plan view of a piezoelectric three-axis acceleration sensor according to another embodiment of the present invention, and FIG. 3B is a plan view of FIG.
It is a BB sectional view taken on the line of (A). FIG. 2 is a plan view of an acceleration sensor used in the acceleration detection device according to the embodiment of the present invention.

FIG. 4 (A) shows the spontaneous polarization charge of the Z-axis acceleration detecting electrode when the acceleration in the Z-axis direction acts on the additional weight in the piezoelectric triaxial acceleration sensor of the embodiment shown in FIG. It is a figure used for description, and (B) is a mimetic diagram used for explaining spontaneous polarization charge of the electrode for Z-axis acceleration detection when acceleration in the direction of the Y-axis acts on an additional weight.

FIG. 5 is a diagram showing a basic electrode pattern formed on the surface of a piezoelectric ceramic substrate used in a conventional piezoelectric three-axis acceleration sensor.

FIG. 6A is a diagram illustrating a conventional piezoelectric three-axis acceleration sensor in which X-axis acceleration is applied to an additional weight,
It is a figure used for explaining the spontaneous polarization charge of the electrode for axial acceleration detection, (B) explains the spontaneous polarization charge of the electrode for Z-axis acceleration detection when acceleration in the Z-axis direction acts on an additional weight. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Diaphragm 1b Diaphragm extension part 3 Weight 5 Base 7, 37 Additional weight 9 Acceleration detecting element 9a, 39a Piezoelectric ceramic substrate 21 Substrate extension piece segment 23 Diaphragm extension segment E1, E11 Detection electrode pattern E2, E12 Counter electrode pattern DX1 , DX2 X-axis acceleration detection electrodes DY1, DY2 Y-axis acceleration detection electrodes DZ1 to DZ4, DZ1 'to DZ4' Z-axis acceleration detection electrodes

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsutomu Sawai 3158 Shimookubo, Osawano-cho, Kamishinkawa-gun, Toyama F-term (reference) 2F051 AA21 AB08 AC01 DA03

Claims (11)

[Claims] An X-axis acceleration detection electrode, a Y-axis acceleration detection electrode, and a Z-axis acceleration detection electrode for detecting three-axis accelerations in an X-axis direction, a Y-axis direction, and a Z-axis direction which are orthogonal to each other. A piezoelectric ceramic substrate having an electrode on the front surface and a counter electrode on the back surface facing each of the detection electrodes; a diaphragm having the front surface joined to the back surface of the piezoelectric ceramic substrate; and a center of the back surface of the diaphragm And a base supporting the diaphragm so that a portion of the piezoelectric ceramic substrate around the weight is bent when the acceleration acts on the weight. A three-axis acceleration sensor, wherein the X-axis acceleration detection electrode and the Y-axis acceleration detection electrode are located in front of the piezoelectric ceramic substrate caused by displacement of the weight. The piezoelectric ceramic substrate and the diaphragm are respectively disposed so as to obtain an X-axis acceleration detection signal and a Y-axis acceleration detection signal by spontaneous polarization charges generated by bending of the portion. An additional weight is provided on the back surface of the diaphragm extension, and the Z-axis acceleration detecting electrode is a spontaneously polarized charge generated by the deflection of the substrate extension caused by the displacement of the additional weight. A piezoelectric type three-axis acceleration sensor, which is disposed on the surface of the substrate extension so as to obtain a Z-axis acceleration detection signal. 2. The piezoelectric triaxial acceleration sensor according to claim 1, wherein the diaphragm, the weight, the base, and the additional weight are integrally formed. 3. The piezoelectric device according to claim 1, wherein the base has a cylindrical shape, and the additional weight has a cylindrical shape concentrically arranged with the base. Axial acceleration sensor. 4. The Z-axis acceleration detecting electrode includes at least one pair, one Z-axis acceleration detecting electrode is disposed adjacent to the base, and the other Z-axis acceleration detecting electrode is adjacent to the additional weight. 4. The piezoelectric device according to claim 3, wherein the portions of the substrate extension corresponding to the one Z-axis acceleration detection electrode and the other Z-axis acceleration detection electrode are polarized to have opposite polarities. Type three-axis acceleration sensor. 5. The substrate extension portion is constituted by one or more pairs of substrate extension piece segments arranged at intervals of 180 degrees in a circumferential direction, and the diaphragm extension portion is formed by the paired substrate segments. The Z-axis acceleration detection electrodes are provided corresponding to the pair of substrate extension piece segments, respectively. The Z-axis acceleration detection electrodes are provided corresponding to the pair of substrate extension piece segments. 3. The method according to claim 1, wherein the additional weight is provided.
3. The piezoelectric three-axis acceleration sensor according to 1. 6. The piezoelectric three-axis acceleration sensor according to claim 5, wherein portions of the substrate extension piece segments corresponding to the Z-axis acceleration detection electrodes are respectively polarized to have the same polarity. 7. A pair of X-axis acceleration detecting electrodes, a pair of Y-axis acceleration detecting electrodes, and a pair of electrodes for detecting three-axis accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction orthogonal to each other. A piezoelectric ceramic substrate having the above-described Z-axis acceleration detecting electrode on the front surface and having at least one counter electrode on the back surface facing each of the detection electrodes, and the back surface of the piezoelectric ceramic substrate bonded to the front surface; A diaphragm provided at a central portion of a back surface of the diaphragm, and a portion which is bent so that a portion of the piezoelectric ceramic substrate around the weight is generated when the acceleration acts on the weight. A piezoelectric three-axis acceleration sensor comprising a cylindrical base that supports a diaphragm, wherein the pair of X-axis acceleration detection electrodes are arranged in the X-axis direction with the weight interposed therebetween. The portions of the piezoelectric ceramic substrate corresponding to the pair of X-axis acceleration detecting electrodes are respectively polarized in opposite polarities, and the pair of Y-axis acceleration detecting electrodes are arranged in the Y-axis direction with the weight interposed therebetween. The portions of the piezoelectric ceramic substrate corresponding to the pair of Y-axis acceleration detection electrodes are arranged in parallel, and the portions of the piezoelectric ceramic substrate are respectively polarized in opposite polarities, and the piezoelectric ceramic substrate and the diaphragm each have a substrate extension extending outside the base. A diaphragm extending portion is provided; an additional weight having a cylindrical shape is provided concentrically with the base at an outer end of a back surface of the diaphragm extending portion; and one Z-axis of the pair of Z-axis acceleration detecting electrodes is provided. The acceleration detection electrode is disposed adjacent to the base, the other Z-axis acceleration detection electrode is disposed adjacent to the additional weight,
A piezoelectric three-axis acceleration sensor, wherein each part of the substrate extension corresponding to the one Z-axis acceleration detecting electrode and the other Z-axis acceleration detecting electrode is polarized to have opposite polarities. 8. The one Z-axis acceleration detecting electrode is formed so as to enter a region of the piezoelectric ceramic substrate facing the base, and the other Z-axis acceleration detecting electrode is provided on the substrate extension part. The piezoelectric triaxial acceleration sensor according to claim 7, wherein the piezoelectric three-axis acceleration sensor is formed so as to straddle a region facing the additional weight and a region not facing the additional weight. 9. A pair of X-axis acceleration detection electrodes, a pair of Y-axis acceleration detection electrodes, and a pair of X-axis acceleration detection electrodes for detecting three-axis accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction, which are orthogonal to each other. A piezoelectric ceramic substrate having a pair of Z-axis acceleration detecting electrodes on the front surface and one or more opposing electrodes on the back surface facing the detection electrodes, and the back surface of the piezoelectric ceramic substrate being joined to the front surface A diaphragm provided at a central portion of a back surface of the diaphragm, and a portion which is bent so that a portion of the piezoelectric ceramic substrate around the weight is generated when the acceleration acts on the weight. A piezoelectric triaxial acceleration sensor comprising a cylindrical base supporting a diaphragm, wherein the pair of X-axis acceleration detecting electrodes are arranged in the X-axis direction with the weight interposed therebetween. The portions of the piezoelectric ceramic substrate corresponding to the pair of X-axis acceleration detecting electrodes are respectively polarized in opposite polarities, and the pair of Y-axis acceleration detecting electrodes are arranged in the Y-axis direction with the weight therebetween. The portions of the piezoelectric ceramic substrate corresponding to the pair of Y-axis acceleration detection electrodes are respectively polarized in opposite polarities, and the piezoelectric ceramic substrate and the diaphragm each include a substrate extension extending outside the base and A diaphragm extension portion is provided, wherein the substrate extension portion is constituted by a pair of substrate extension piece segments extending outward in the X-axis direction and a pair of substrate extension piece segments extending outward in the Y-axis direction; The substrate comprises two pairs of diaphragm extension segments supporting the substrate extension segment, The Z-axis acceleration detecting electrode is provided on each of the long piece segments, and the additional weight is provided on each of the plurality of diaphragm extension segments, one for each of the Z-axis acceleration detecting electrodes. A piezoelectric triaxial acceleration sensor, wherein the portions of the piezoelectric ceramic substrate are polarized to have the same polarity. 10. The Z-axis acceleration detecting electrode is formed so as to extend over a region of the substrate extension piece segment facing the weight and a region not facing the weight. 10. The piezoelectric triaxial acceleration sensor according to item 9. 11. A plurality of X-axis acceleration detection electrodes, a plurality of Y-axis acceleration detection electrodes, and a plurality of Y-axis acceleration detection electrodes for detecting three-axis accelerations in X-axis, Y-axis, and Z-axis directions orthogonal to each other. A piezoelectric ceramic substrate having a Z-axis acceleration detection electrode on the front surface and having a counter electrode on the back surface facing each of the detection electrodes, a diaphragm having the front surface joined to the back surface of the piezoelectric ceramic substrate, A weight provided at the center of the back surface of the diaphragm, and supporting the diaphragm such that when the acceleration acts on the weight, a portion of the piezoelectric ceramic substrate around the weight is bent. A piezoelectric type triaxial acceleration sensor comprising: a base; a part of the plurality of Z-axis acceleration detecting electrodes;
The electrode for axis acceleration detection and the electrode for Y axis acceleration detection,
Part of the Z-axis acceleration detection signal, the X-axis acceleration detection signal, and the Y-axis acceleration detection signal are generated by spontaneous polarization charges generated by bending of the portion of the piezoelectric ceramic substrate caused by displacement of the weight.
The piezoelectric ceramic substrate and the diaphragm are respectively provided with a substrate extension and a diaphragm extension extending outside the base, and an additional weight is provided on the back surface of the diaphragm extension. A weight is provided, and the remaining electrodes of the plurality of Z-axis acceleration detection electrodes are configured such that the remainder of the Z-axis acceleration detection signal is generated by spontaneous polarization charges generated by bending of the substrate extension caused by displacement of the additional weight. A piezoelectric three-axis acceleration sensor, which is disposed on the surface of the substrate extension so as to be obtained.