Piezoelectric element and manufacturing method thereof, sensor assembly and electronic device

Abstract

The present invention relates to the technical field of piezoelectric sensors, and specifically to a piezoelectric element and a method for manufacturing the same, a sensor assembly and an electronic device. The piezoelectric element comprises: a piezoelectric ceramic, which is an annular piezoelectric ceramic, polarized to form an axial polar axis and coated with electrodes on the inner and outer sides of the annulus; and a radial polarization zone and an axial polarization zone located on the piezoelectric ceramic, the piezoelectric ceramic is provided with a slot, an electrode block with the same width as the slot is removed from the outer circumferential surface of the piezoelectric ceramic, and the slot and the removal of the electrode block separate the piezoelectric ceramic into a radial polarization zone and an axial polarization zone. The piezoelectric element manufactured by the present invention comprises two polarization axes and three partition electrodes, and a three-axis piezoelectric acceleration sensor assembly is formed by assembling a piece of the manufactured piezoelectric ceramic element to realize vibration or impact monitoring in three directions, so that the sensor assembly has the advantages of small size, low noise, wide frequency band, easy manufacturing, high reliability and low cost.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of piezoelectric sensors, and in particular to a piezoelectric element and a manufacturing method thereof, a sensor assembly and an electronic device. Background Art

[0002] A piezoelectric accelerometer is a sensor that can measure acceleration. Its principle is to use the piezoelectric effect of a piezoelectric element. Under acceleration, the inertial mass of the accelerometer causes a displacement current in the piezoelectric element, thereby generating an electrical output that is proportional to the acceleration.

[0003] Among them, the triaxial piezoelectric accelerometer can measure vibration or impact acceleration in three directions of space at the same time. The well-known triaxial piezoelectric accelerometer mainly adopts two schemes:

[0004] 1. Three unidirectional acceleration sensors with independent outputs are installed in a metal shell, that is, three brackets, three piezoelectric elements and three mass blocks are installed vertically together;

[0005] 2. Shear and compression coincident triaxial piezoelectric accelerometer, which combines three groups of piezoelectric elements in a way that the maximum sensitivity axes are perpendicular to each other and then installed on a base, that is, using a bracket, at least three piezoelectric elements, and a mass block, and then an inertial mass block is installed on the piezoelectric element for pre-tightening.

[0006] In order to realize three-axis detection, the above two solutions need to use at least three piezoelectric elements, and the sensitivity axes of the elements are perpendicular to each other. This will make the volume and weight of the sensor larger and the cost higher, and also lead to problems such as low natural frequency, narrow frequency response, and low sensitivity and accuracy. Summary of the invention

[0007] The purpose of the embodiments of the present invention is to provide a piezoelectric element and a manufacturing method thereof, a sensor assembly and an electronic device, which are applied to a three-axis piezoelectric acceleration sensor, aiming to be able to realize charge output in three directions through a piezoelectric ceramic element. The manufactured piezoelectric element realizes charge output in three directions through two polarization axes and three partition electrodes. The sensor assembly using the piezoelectric element can realize vibration or impact monitoring in three directions through one piezoelectric element.

[0008] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions.

[0009] In a first aspect, in an embodiment provided by the present invention, a piezoelectric element is provided, comprising:

[0010] Piezoelectric ceramics, the piezoelectric ceramics are ring-shaped piezoelectric ceramics, the piezoelectric ceramics are polarized to form an axial polar axis and electrodes are plated on the inner and outer sides of the ring;

[0011] A radial polarization region and an axial polarization region are located on the piezoelectric ceramic, the piezoelectric ceramic is provided with a groove, an electrode block 1 having the same width as the groove is removed from the outer circumferential surface of the piezoelectric ceramic, and the groove and the removal of the electrode block 1 separate the piezoelectric ceramic into a radial polarization region and an axial polarization region;

[0012] Among them, the electrode block 2 is removed from the center position of the outer cylindrical surface of the piezoelectric ceramic in the radial polarization zone to form a first radial polarization zone and a second radial polarization zone. The first radial polarization zone, the second radial polarization zone and the axial polarization zone are spaced apart from each other to form a piezoelectric element.

[0013] The first radial polarization zone, the second radial polarization zone and the axial polarization zone in the piezoelectric element of the embodiment of the present invention are spaced apart from each other, and charge output in three directions is achieved by means of a single-chip piezoelectric ceramic element, two polarization axes and three partitioned electrodes. There is no need to use at least three piezoelectric elements installed perpendicularly to each other to achieve the purpose of a three-axis piezoelectric acceleration sensor that can simultaneously measure vibration or impact acceleration in three directions of space. This can be accomplished using one piezoelectric element, which greatly reduces the number of piezoelectric elements used, can reduce the volume and weight of the sensor, and reduce costs. Moreover, it is helpful to solve the problems of low natural frequency, narrow frequency response, and low sensitivity and accuracy of the sensor.

[0014] In some embodiments provided by the present invention, the groove on the piezoelectric ceramic is a through-cut groove, and the angle between the electrode block 1 in the axial polarization zone and the groove is α, 0°<α<360°.

[0015] A slot that passes through the truncation notch is formed on the piezoelectric element of the embodiment of the present invention, and an electrode block is cut off at the other end of the axial polarization zone to prevent the annular piezoelectric ceramic from breaking and separating the radial polarization zone and the axial polarization zone. When the radial polarization zone and the axial polarization zone are formed, the connection is more stable, and the size of the division between the radial polarization zone and the axial polarization zone can be selected according to the size of the angle α.

[0016] In some embodiments provided by the present invention, the electrode block 2 removed from the center of the radial polarization zone is an electrode with the same width as the slot cut out along the outer cylindrical surface of the piezoelectric ceramic, and the radial polarization zone is divided into two equal parts to form a first radial polarization zone and a second radial polarization zone of equal size.

[0017] The piezoelectric element of the embodiment of the present invention divides the outer circumferential surface of the radial polarization part into two equal parts, and the axial polarization partition and the first radial polarization zone and the second radial polarization zone form three partitions, so that one piezoelectric element can realize vibration or impact monitoring in three directions.

[0018] In some embodiments provided by the present invention, the polarization directions of the first radial polarization zone and the second radial polarization zone are distributed radially along the annular piezoelectric ceramic, and the polarization directions of the first radial polarization zone and the second radial polarization zone are distributed radially from the outside to the inside or from the inside to the outside along the annular piezoelectric ceramic.

[0019] In a second aspect, in an embodiment provided by the present invention, a method for manufacturing a piezoelectric element is provided, the manufacturing method comprising:

[0020] Providing annular piezoelectric ceramics;

[0021] Silver electrodes are printed on the end surface of the annular piezoelectric ceramic and polarized to form an axial polar axis;

[0022] After removing the electrode on the end face of the annular piezoelectric ceramic, use chemical plating or sputtering to plate electrodes on the inside and outside of the annular piezoelectric ceramic, and the electrodes fully cover the annular piezoelectric ceramic to a short-circuit state. After removing the end face electrode of the annular piezoelectric ceramic, the electrodes on the inner and outer sides of the annular piezoelectric ceramic are in an open-circuit state.

[0023] A groove is cut on the side of the annular piezoelectric ceramic, and an electrode block having a width equal to the groove is removed along the outer circumference of the annular piezoelectric ceramic at an angle α from the groove, so that the annular piezoelectric ceramic forms a radial polarization zone and an axial polarization zone;

[0024] The second electrode block is removed from the center of the outer circumferential surface of the annular piezoelectric ceramic in the radial polarization zone to form a first radial polarization zone and a second radial polarization zone of equal size;

[0025] The annular piezoelectric ceramic is aged and subjected to high and low temperature cycle treatment to obtain a first radial polarization region, a second radial polarization region and an axial polarization region which are spaced apart from each other to form a piezoelectric element.

[0026] In some embodiments provided by the present invention, the annular piezoelectric ceramic is aged at 3 / 5 of the Curie temperature of the piezoelectric ceramic for 48-96 hours, and is cycled between a low temperature of -65 to -55°C and a high temperature of 120 to 150°C for 10 to 20 cycles to obtain the desired piezoelectric element.

[0027] In a third aspect, in an embodiment provided by the present invention, a sensor component is provided, the sensor component comprising:

[0028] A ceramic element, wherein the ceramic element is a piezoelectric element composed of the first radial polarization region, the second radial polarization region, and the axial polarization region described in any one of the above embodiments, which are spaced apart from each other;

[0029] A base, for mounting the ceramic element on the base;

[0030] A mass block, located outside the ceramic element and used to limit the position of the ceramic element; and

[0031] The fixing part is located outside the mass block and is used to fix the mass block and the ceramic element on the base.

[0032] In some embodiments provided by the present invention, the fixing member is a memory metal ring or a clamping ring.

[0033] In some embodiments provided by the present invention, the sensor assembly is a three-axis piezoelectric acceleration sensor, one of the three axes of the three-axis piezoelectric acceleration sensor is parallel to the polar axis direction of the axial polarization zone of the piezoelectric element, and one of the other two axes of the three-axis piezoelectric acceleration sensor is aligned with the center line of electrode block 2 between the first radial polarization zone and the second radial polarization zone of the piezoelectric element.

[0034] In a fourth aspect, in an embodiment provided by the present invention, an electronic device is provided, the electronic device comprising:

[0035] The sensor assembly described in any one of the above embodiments.

[0036] Compared with the prior art, the piezoelectric element and its manufacturing method, sensor assembly and electronic device provided in the embodiments of the present invention, the manufactured piezoelectric element includes two polarization axes and three partitioned electrodes, and a three-axis piezoelectric acceleration sensor assembly is formed by assembling a piece of the manufactured piezoelectric ceramic element. The sensor assembly realizes vibration or impact monitoring in three directions through a piezoelectric element, so that the sensor assembly has the advantages of small size, low noise, wide frequency band, easy manufacturing, high reliability and low cost.

[0037] These and other aspects of the present invention will be more clearly understood in the following description of the embodiments. It should be understood that the above general description and the following detailed description are only exemplary and explanatory and cannot limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0039] Figure 1 The figure is a top view of a piezoelectric element according to an embodiment of the present invention.

[0040] Figure 2 The figure is a side view of a piezoelectric element according to an embodiment of the present invention.

[0041] Figure 3 This is a schematic structural diagram of a piezoelectric element in an embodiment of the present invention when the axial partition is 120°.

[0042] Figure 4This is a schematic diagram of the X-axis force on a three-axis sensor of a piezoelectric element in which the axial partition is 120° in an embodiment of the present invention.

[0043] Figure 5 This is a schematic diagram of the Y-axis force on a three-axis sensor of a piezoelectric element in which the axial partition is 120° in an embodiment of the present invention.

[0044] Figure 6 This is a schematic structural diagram of a piezoelectric element in an embodiment of the present invention when the axial partition is 180°.

[0045] Figure 7 It is a side schematic diagram of a piezoelectric element in an embodiment of the present invention when the axial partition is 180°.

[0046] Figure 8 This is a schematic diagram of the X-axis force on a three-axis sensor of a piezoelectric element in which the axial partition is 180° in an embodiment of the present invention.

[0047] Fig. 9 This is a schematic diagram of the Y-axis force on a three-axis sensor of a piezoelectric element in which the axial partition is 180° in an embodiment of the present invention.

[0048] Fig.10 It is a front view of a three-axis piezoelectric acceleration sensor assembly in a sensor assembly according to an embodiment of the present invention.

[0049] Fig.11 The present invention is a schematic structural diagram of a triaxial piezoelectric acceleration sensor assembly in a sensor assembly according to an embodiment of the present invention.

[0050] Reference numerals:

[0051] 1-ceramic element; 11-axial polarization zone; 12-first radial polarization zone; 13-second radial polarization zone; 14-slot; 15-electrode block 1; 16-electrode block 2;

[0052] 2-base; 3-mass block; 4-fixing part. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0054] At present, the three-axis piezoelectric acceleration sensor can measure the vibration or impact acceleration in three directions of space at the same time. It mainly relies on installing three unidirectional acceleration sensors with independent output in a metal shell, and installing three brackets, three piezoelectric elements and three mass blocks 3 perpendicularly to each other to form a sensor assembly. At the same time, in order to realize the detection of three axes, the shear and compression overlap type three-axis piezoelectric acceleration sensor of another type also needs to use at least three piezoelectric elements, and the sensitivity axes of the elements are perpendicular to each other. This will make the volume and weight of the sensor larger and the cost higher, and at the same time lead to problems such as low natural frequency, narrow frequency response, and low sensitivity and accuracy.

[0055] To solve the above problems, the present invention provides a piezoelectric element and a manufacturing method thereof, a sensor assembly and an electronic device, which can realize charge output in three directions through a piezoelectric ceramic element. The manufactured piezoelectric element realizes charge output in three directions through two polarization axes and three partition electrodes. The sensor assembly using the piezoelectric element can realize vibration or impact monitoring in three directions through one piezoelectric element.

[0056] The following description of at least one exemplary embodiment is merely illustrative and is not intended to limit the disclosure of the present invention and its application or use. It should be noted that the features in the embodiments of the present invention may be combined with each other without conflict.

[0057] Specifically, the embodiments of the present application are further described below in conjunction with the accompanying drawings.

[0058] Example 1

[0059] like Figure 1 and Figure 2 As shown, one embodiment of the present invention provides a piezoelectric element, which includes a piezoelectric ceramic. In this embodiment, the piezoelectric ceramic is a ring-shaped piezoelectric ceramic, the piezoelectric ceramic is polarized to form an axial polar axis, and electrodes are plated on the inner and outer sides of the ring.

[0060] Among them, the piezoelectric element also includes a radial polarization zone and an axial polarization zone 11 located on the piezoelectric ceramic, a groove 14 is provided on the piezoelectric ceramic, and an electrode block 15 with the same width as the groove 14 is removed from the outer cylindrical surface of the piezoelectric ceramic. The groove 14 and the removal of the electrode block 15 separate the piezoelectric ceramic into a radial polarization zone and an axial polarization zone 11.

[0061] Moreover, the electrode block 2 16 is removed from the center of the outer cylindrical surface of the piezoelectric ceramic in the radial polarization zone to form a first radial polarization zone 12 and a second radial polarization zone 13. The first radial polarization zone 12, the second radial polarization zone 13 and the axial polarization zone 11 are spaced apart from each other to form a piezoelectric element.

[0062] The first radial polarization zone 12, the second radial polarization zone 13 and the axial polarization zone 11 in the piezoelectric element of the embodiment of the present invention are spaced apart from each other, and charge output in three directions is achieved by means of a single-chip piezoelectric ceramic element, two polarization axes and three partitioned electrodes. There is no need to use at least three piezoelectric elements installed perpendicularly to each other to achieve the purpose of a three-axis piezoelectric acceleration sensor that can simultaneously measure vibration or impact acceleration in three directions of space. This can be accomplished using one piezoelectric element, which greatly reduces the number of piezoelectric elements used, can reduce the volume and weight of the sensor, and reduce costs. Moreover, it is helpful to solve the problems of low natural frequency, narrow frequency response, and low sensitivity and accuracy of the sensor.

[0063] The slot 14 on the piezoelectric ceramic is a through-cut slot, and the angle between the electrode block 15 of the axial polarization zone 11 and the slot 14 is α, 0°<α<360°.

[0064] In one embodiment of the present invention, α = 120°, see Figure 3 As shown, Figure 3 The axial polarization area 11, the first radial polarization area 12 and the second radial polarization area 13 are divided into three equal parts after removing the groove 14, the electrode block 15 and the electrode block 2 16 along the annular piezoelectric ceramic.

[0065] In one embodiment of the present invention, α = 180°, see Figure 6 and Figure 7 As shown, Figure 6 and Figure 7 The schematic diagram of the piezoelectric element with axial division of 180 degrees is shown in FIG. The axial polarization zone 11 is divided into two parts, the axial polarization zone 11 and the radial polarization zone, after the groove 14 and the electrode block 1 15 are removed along the annular piezoelectric ceramic; and the middle part of the radial polarization zone is divided into two parts, the first radial polarization zone 12 and the second radial polarization zone 13, after the electrode block 2 16 is removed.

[0066] A slot 14 that passes through the cutoff notch is formed on the piezoelectric element of the embodiment of the present invention, and an electrode block 15 is cut off at the other end of the axial polarization zone 11 to prevent the annular piezoelectric ceramic from breaking and separating the radial polarization zone and the axial polarization zone 11. When the radial polarization zone and the axial polarization zone 11 are formed, the connection is more stable, and the size of the division of the radial polarization zone and the axial polarization zone 11 can be selected according to the size of the angle α.

[0067] The electrode block 2 16 removed from the center of the radial polarization zone is an electrode cut along the outer circumferential surface of the piezoelectric ceramic with the same width as the slot 14 , and the radial polarization zone is divided into two equal parts to form a first radial polarization zone 12 and a second radial polarization zone 13 of equal size.

[0068] The piezoelectric element of the embodiment of the present invention divides the outer circumferential surface of the radial polarization part into two equal parts, and the axial polarization partition and the first radial polarization zone 12 and the second radial polarization zone 13 form three partitions, so that one piezoelectric element can realize vibration or impact monitoring in three directions.

[0069] The polarization directions of the first radial polarization zone 12 and the second radial polarization zone 13 are distributed radially along the annular piezoelectric ceramic, and the polarization directions of the first radial polarization zone 12 and the second radial polarization zone 13 are distributed radially from outside to inside or from inside to outside along the annular piezoelectric ceramic.

[0070] It is important to note that, see Figure 1 As shown, the electrode block 15 and the electrode block 2 16 removed from the piezoelectric ceramic have no electrodes, and the polarization direction of the first radial polarization region 12 and the second radial polarization region 13 is radial polarization, see Figure 1 As shown, the radial polarization direction can be outward, as indicated by the arrow from inside to outside, or inward, from outside to inside. The polarization direction of the axial polarization zone 11 is along the axial polarization of the piezoelectric ceramic.

[0071] The piezoelectric element of the present invention forms a first radial polarization zone 12, a second radial polarization zone 13 and an axial polarization zone 11 which are spaced apart from each other, and realizes charge output in three directions through a piezoelectric ceramic element. There is no need to use at least three piezoelectric elements installed perpendicularly to each other to achieve the purpose of a three-axis piezoelectric acceleration sensor that can simultaneously measure vibration or impact acceleration in three directions of space. This can be accomplished using one piezoelectric element, which greatly reduces the number of piezoelectric elements used, can reduce the volume and weight of the sensor, and reduce costs. In addition, it is helpful to solve the problems of low natural frequency, narrow frequency response, and low sensitivity and accuracy of the sensor.

[0072] Example 2

[0073] An embodiment of the present invention provides a method for manufacturing a piezoelectric element, the method comprising:

[0074] Step S1, providing a ring-shaped piezoelectric ceramic.

[0075] In this embodiment, the annular piezoelectric ceramic is manufactured using a conventional electronic ceramic manufacturing process, wherein the piezoelectric constant of the piezoelectric ceramic is: 33 d 24 =d 15 d 13 =d 23 The value is not zero, and the other piezoelectric constants are 0.

[0076] Step S2: printing silver electrodes on the end faces of the annular piezoelectric ceramics and polarizing them to form an axial polar axis.

[0077] Step S3, after removing the electrode on the end face of the annular piezoelectric ceramic, use chemical plating or sputtering to plate electrodes on the inside and outside of the annular piezoelectric ceramic, and the electrodes fully cover the annular piezoelectric ceramic to a short-circuit state. After removing the end face electrode of the annular piezoelectric ceramic, the electrodes on the inner and outer side surfaces of the annular piezoelectric ceramic are in an open-circuit state.

[0078] In this embodiment, the purpose of forming the electrode on the end face of the annular piezoelectric ceramic is to form an axial polarization axis. The purpose of removing the electrode is that this electrode will not be used later, mainly the side electrode. When forming the side electrode, the electrode is plated on the inner and outer sides of the ring by chemical plating or sputtering, and then the end face electrode is removed.

[0079] In this embodiment, the inner and outer electrodes are plated to extract the charge generated by the piezoelectric ceramic under force. Since the inner and outer electrodes cannot be removed, the electrode plating in this application refers to the electrode plating on the ring by chemical plating or sputtering. The electrode will be fully covered, and the entire ceramic ring is in a short-circuit state. After removing the end face, the inner and outer side electrodes are in an open-circuit state.

[0080] Step S4, cutting a groove 14 on the side of the annular piezoelectric ceramic, and removing an electrode block 15 with the same width as the groove 14 along the outer circumferential surface of the annular piezoelectric ceramic at an angle α from the groove, so that the annular piezoelectric ceramic forms a radial polarization region and an axial polarization region 11.

[0081] In this embodiment, a slot 14 with a width of N mm (the size of N is designed according to actual needs, for example: N = 0.1 mm) is cut on the side of the annular piezoelectric ceramic. Figure 1 At the same time, an electrode block 15 having the same width as the slot 14 is removed along the outer cylindrical surface of the annular piezoelectric ceramic leaving the slot at an angle of α (0°<α<360°), and the outer cylindrical electrode is divided into two zones: a radial polarization zone and an axial polarization zone 11.

[0082] Step S5, removing the second electrode block 16 at the center of the outer circumferential surface of the annular piezoelectric ceramic in the radial polarization zone, and dividing it into two equal parts to form a first radial polarization zone 12 and a second radial polarization zone 13 of equal size.

[0083] In this embodiment, the electrode block 16 having the same width as the slot 14 is removed from the center of the outer circumferential surface of the radial polarization zone, so that the outer circumferential surface of the radial polarization zone is divided into two equal parts, and the axial polarization zone 11 and the two partitions of the radial polarization zone are formed as follows: Figure 1 Shown are: an axial polarization zone 11, a first radial polarization zone 12 and a second radial polarization zone 13.

[0084] It should be particularly noted that the two partitions of the first radial polarization zone 12 and the second radial polarization zone 13 must be equal in size, and then the two partitions of equal size are polarized in the radial direction.

[0085] Step S6, aging the annular piezoelectric ceramic and subjecting it to high and low temperature cycle treatment to obtain a piezoelectric element composed of the first radial polarization region 12, the second radial polarization region 13 and the axial polarization region 11 which are spaced apart from each other.

[0086] In this embodiment, the annular piezoelectric ceramic is aged at 3 / 5 of the Curie temperature of the piezoelectric ceramic for 48-96 hours, and is cycled between a low temperature of -65 to -55°C and a high temperature of 120 to 150°C for 10 to 20 cycles to obtain the desired piezoelectric element.

[0087] In an embodiment of the present invention, a method for manufacturing a piezoelectric ceramic element realizes charge output in three directions through two polarization axes and three partition electrodes. A ring-shaped piezoelectric ceramic is manufactured using a traditional electronic ceramic manufacturing process, and a silver electrode is printed on the end face, polarized, and an axial polar axis is formed. Charge output in three directions is realized by a single-chip piezoelectric ceramic element, two polarization axes, and three partition electrodes. The manufacturing is convenient and quick. The manufactured piezoelectric element includes two polarization axes and three partition electrodes. A three-axis piezoelectric acceleration sensor assembly is formed by assembling a manufactured piezoelectric ceramic element. The sensor assembly realizes vibration or impact monitoring in three directions through a piezoelectric element, so that the sensor assembly has the advantages of small size, low noise, wide bandwidth, easy manufacturing, high reliability, and low cost.

[0088] Example 3

[0089] like Fig.10 and Fig.11 As shown, an embodiment of the present invention provides a sensor assembly, which includes a ceramic element 1, a base 2, a mass block 3 and a fixing member 4. The ceramic element 1 is a piezoelectric element composed of the first radial polarization zone 12, the second radial polarization zone 13 and the axial polarization zone 11 described in any one of the above embodiments, which are spaced apart from each other. The ceramic element 1 is mounted on the base 2, and the mass block 3 is located outside the ceramic element 1, which is used to limit the ceramic element 1. The fixing member 4 is located outside the mass block 3, and the fixing member 4 is used to fix the mass block 3 and the ceramic element 1 on the base 2.

[0090] In the embodiment of the present invention, the fixing member 4 is a memory metal ring or a clamping ring.

[0091] The sensor assembly is a three-axis piezoelectric acceleration sensor, one of the three axes of the three-axis piezoelectric acceleration sensor is parallel to the polar axis direction of the axial polarization zone 11 of the piezoelectric element, and one of the other two axes of the three-axis piezoelectric acceleration sensor is aligned with the center line of the electrode block 2 16 between the first radial polarization zone 12 and the second radial polarization zone 13 of the piezoelectric element.

[0092] During assembly, one of the three axes of the piezoelectric element in the three-axis piezoelectric sensor design must be equal to the polar axis direction of the axial polarization partition 11, and one of the other two axes must be aligned with the center line of electrode block 2 16 between the first radial polarization zone 12 and the second radial polarization zone 13.

[0093] See also Fig.11 As shown, a memory metal ring or clamping ring (mass m1) is used to fix the mass block 3 (mass m2) ceramic element on the base to obtain the required three-axis piezoelectric acceleration sensor assembly.

[0094] In one embodiment of the present invention, the base 2 may be used as the mass block 3, and the memory metal ring or clamp ring may be used as the fixing device, and the assembly method remains unchanged.

[0095] It should be particularly noted that the axial polarization region 11 , the first radial polarization region 12 , and the second radial polarization region 13 can be any axis of the three-axis sensor according to design requirements.

[0096] The three-axis piezoelectric acceleration sensor assembly assembled using the above-mentioned piezoelectric element in the embodiment of the present invention can realize vibration or impact monitoring in three directions through one piezoelectric element, and has the advantages of small size, low noise, wide frequency band, easy manufacturing, high reliability and low cost.

[0097] Example 4

[0098] An embodiment of the present invention provides an electronic device, comprising: a sensor assembly as described in any one of the above embodiments.

[0099] The piezoelectric element and its manufacturing method, sensor assembly and electronic device provided in the embodiments of the present invention realize charge output in three directions through a single-chip piezoelectric ceramic element, two polarization axes and three partition electrodes. At the same time, a three-axis piezoelectric acceleration sensor assembly assembled with piezoelectric elements aligns one of the three axes with the polar axis direction of the axial polarization partition, and aligns one of the other two axes with the center line of the electrode block 216 between the equally divided radial partitions, so that vibration or impact monitoring in three directions can be realized. It has a small size, low noise, and a widened frequency band, and can be used for the detection of earthquakes, buildings, dams, mines, etc.; it can also be used for military deployment, early warning, submarine detection, landslide detection, etc.

[0100] The piezoelectric element and its manufacturing method, sensor assembly and electronic device provided by the present invention have the following conditions for the charge output of the piezoelectric element and the sensitivity output of the sensor in each direction after being subjected to forces in three directions:

[0101] 1. Analysis of the force in the Z-axis direction, the charge of the piezoelectric element, the sensitivity in the Z-axis direction of the component, and the lateral sensitivity.

[0102] Taking the axial polarization zone 11 as the axial polarization, the first radial polarization zone 12 and the second radial polarization zone 13 are subjected to a force of acceleration η (η>0) times the gravitational acceleration g in the Z-axis direction (vertical direction), and the magnitude is F Z =(m1+m2)×η×g, theoretical calculation of the charge output by the piezoelectric element and the sensitivity of the sensor component.

[0103] The axial polarization region 11 is subjected to shear force at this time. According to the piezoelectric equation, the charge output by the piezoelectric element in the axial polarization region 11 is:

[0104] Q 11 =F Z ×d 24 =(m1+m2)×η×g×d 24

[0105] Because: 15 =d 24 ;

[0106] but

[0107] Q 11 =F Z ×d 24 =(m1+m2)×η×g×d 15

[0108] The first radial polarization region 12 and the second radial polarization region 13 are also subjected to shear force. According to the piezoelectric equation, the magnitude of the charge output by the piezoelectric element in the first radial polarization region 12 and the second radial polarization region 13 is:

[0109] Q 12 =Q 13 =F Z ×d 34 =(m1+m2)×η×g×d 34

[0110] And because

[0111] d 34 =0

[0112] therefore

[0113] Q 12 =Q 13 =0

[0114] Therefore, the Z-axis direction (vertical direction) is subjected to a force with an acceleration equal to η times the gravitational acceleration g.

[0115] The piezoelectric element has charge only in the Z-axis direction, but no charge output in the X-axis and Y-axis directions.

[0116] therefore:

[0117] Q=Q11 =(m1+m2)×η×g×d 15 =(m1+m2)×η×g×d 15

[0118] The sensor component has no sensitivity output in the X-axis and Y-axis directions, only sensitivity output in the Z-axis direction.

[0119] It can be obtained that the charge sensitivity S in the Z direction is Z :

[0120]

[0121] 2. Analysis of force in the X-axis direction, charge of piezoelectric elements, X-axis sensitivity and lateral sensitivity of components.

[0122] X-axis direction (horizontal direction, such as Figure 4 and Figure 8 As shown in the figure, the force is η (η>0) times the gravitational acceleration g, and its magnitude is F X =(m1+m2)×η×g, theoretical calculation of the charge output by the piezoelectric element and the sensitivity of the sensor component:

[0123] The axially polarized axially polarized region 11 is subjected to shear force at this time. According to the piezoelectric equation, the charge output by the piezoelectric element in the axially polarized region 11 is:

[0124] Q 11 =d X ×d 25 =(m1+m2)×η×g×d 25

[0125] Due to d 15 =d 24 =0

[0126] but

[0127] Q 11 =F X ×d 24 =(m1+m2)×η×g×d 25 =0

[0128] The polar axes of the radially polarized first radial polarization zone 12 and the second radial polarization zone 13 are in opposite directions, and the forces are the same in magnitude but in opposite directions, and α is the angle between the polar axis and the force.

[0129] According to the piezoelectric equation, the force on the piezoelectric element in the first radial polarization zone 12 is F X , the angle between the axis and the force is The output charge is:

[0130] In the X-axis direction

[0131]

[0132] In the Y-axis direction

[0133]

[0134] According to the piezoelectric equation, the force on the piezoelectric element in the second radial polarization zone 13 is -F X , the angle between the axis and the force is The output charge is:

[0135] In the X-axis direction

[0136]

[0137] In the Y-axis direction

[0138]

[0139] The piezoelectric element has no charge output in the Z-axis direction, while the charge output in the X-axis and Y-axis directions are:

[0140] The charge output on the X axis

[0141]

[0142] The charge output on the Y axis

[0143]

[0144] Therefore, when the force is applied in the X-axis direction, the piezoelectric element only generates charge in the X-axis direction, while there is no charge output in the Y-axis and Z-axis directions.

[0145] Therefore, the total charge output by the piezoelectric element is:

[0146] Q=Q 11 +Q X +Q Y =0+(-3×(m1+m2)×η×g×d 33 )+0

[0147] =-3×(m1+m2)×η×g×d 33

[0148] The sensor component has no sensitivity output in the Y-axis and Z-axis directions, only sensitivity output in the X-axis direction.

[0149] therefore

[0150]

[0151] 3. Analysis of the force in the Y-axis direction, the charge of the piezoelectric element, the sensitivity of the component in the Y-axis direction and the lateral sensitivity.

[0152] Y-axis direction (horizontal direction, such as Figure 5 and Fig. 9 As shown in the figure, the force is η (η>0) times the gravitational acceleration g, and its magnitude is F Y =(m1+m2)×η×g, theoretical calculation of the charge output by the piezoelectric element and the sensitivity of the sensor component:

[0153] The axially polarized axially polarized region 11 is now under compressive or tensile stress. According to the piezoelectric equation, the charge output by the piezoelectric element in the axially polarized region 11 is:

[0154] Q 11 =F Y ×d 22 =(m1+m2)×η×g×d 22

[0155] Because d 11 =d 22 =0

[0156] but

[0157] Q 11 =F Y ×d 22 =(m1+m2)×η×g×d 22 =0

[0158] The polar axes of the radially polarized first radial polarization zone 12 and the second radial polarization zone 13 are in opposite directions, and the forces are of the same magnitude and direction, and β and γ are the angles between the polar axes and the force.

[0159] According to the piezoelectric equation, the piezoelectric element is in the first radial polarization zone 12, is the angle between the polar axis and the force, and the output charge is:

[0160] In the X-axis direction

[0161]

[0162] In the Y-axis direction

[0163]

[0164] According to the piezoelectric equation, the piezoelectric element is in the second radial polarization region 13, is the angle between the polar axis and the force, and the output charge is:

[0165] In the X-axis direction

[0166]

[0167] In the Y-axis direction

[0168]

[0169] The piezoelectric element has no charge output in the Z-axis direction, while the charge output in the X-axis and Y-axis directions are:

[0170] The charge output on the X axis

[0171]

[0172] The charge output on the Y axis

[0173]

[0174] Therefore, the total charge output by the piezoelectric element is:

[0175]

[0176] The sensor component has no sensitivity output in the X-axis and Z-axis directions, only sensitivity output in the Y-axis direction.

[0177] therefore

[0178]

[0179] In summary, the piezoelectric element and its manufacturing method, sensor assembly and electronic device provided in the embodiments of the present invention, the manufactured piezoelectric element includes two polarization axes and three partitioned electrodes, and a three-axis piezoelectric acceleration sensor assembly is formed by assembling a piece of the manufactured piezoelectric ceramic element. The sensor assembly realizes vibration or impact monitoring in three directions through a piezoelectric element, so that the sensor assembly has the advantages of small size, low noise, wide frequency band, easy manufacturing, high reliability and low cost.

[0180] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A piezoelectric element, characterized in that: include: Piezoelectric ceramics, the piezoelectric ceramics are ring-shaped piezoelectric ceramics, the piezoelectric ceramics are polarized to form an axial polar axis and electrodes are plated on the inner and outer sides of the ring; as well as A radial polarization region and an axial polarization region are located on the piezoelectric ceramic, the piezoelectric ceramic is provided with a groove, an electrode block 1 having the same width as the groove is removed from the outer circumferential surface of the piezoelectric ceramic, and the groove and the removal of the electrode block 1 separate the piezoelectric ceramic into a radial polarization region and an axial polarization region; Among them, the electrode block 2 is removed from the center position of the outer cylindrical surface of the piezoelectric ceramic in the radial polarization zone to form a first radial polarization zone and a second radial polarization zone. The first radial polarization zone, the second radial polarization zone and the axial polarization zone are spaced apart from each other to form a piezoelectric element.

2. The piezoelectric element according to claim 1, wherein The groove on the piezoelectric ceramic is a through-cut groove, and the angle between the electrode block 1 in the axial polarization zone and the groove is α, 0°<α<360°.

3. The piezoelectric element according to claim 2, wherein: The electrode block 2 removed from the center of the radial polarization zone is an electrode with the same width as the slot cut out along the outer circumference of the piezoelectric ceramic, and the radial polarization zone is divided into two equal parts to form a first radial polarization zone and a second radial polarization zone of equal size.

4. The piezoelectric element according to claim 3, wherein: The polarization directions of the first radial polarization zone and the second radial polarization zone are distributed radially along the annular piezoelectric ceramic, and the polarization directions of the first radial polarization zone and the second radial polarization zone are distributed radially from outside to inside or from inside to outside along the annular piezoelectric ceramic.

5. A method for manufacturing a piezoelectric element, characterized in that: The production method comprises: Providing annular piezoelectric ceramics; Silver electrodes are printed on the end surface of the annular piezoelectric ceramic and polarized to form an axial polar axis; After removing the electrode on the end face of the annular piezoelectric ceramic, use chemical plating or sputtering to plate electrodes on the inside and outside of the annular piezoelectric ceramic, and the electrodes fully cover the annular piezoelectric ceramic to a short-circuit state. After removing the end face electrode of the annular piezoelectric ceramic, the electrodes on the inner and outer sides of the annular piezoelectric ceramic are in an open-circuit state. A groove is cut on the side of the annular piezoelectric ceramic, and an electrode block having a width equal to the groove is removed along the outer circumference of the annular piezoelectric ceramic at an angle α from the groove, so that the annular piezoelectric ceramic forms a radial polarization zone and an axial polarization zone; The second electrode block is removed from the center of the outer circumferential surface of the annular piezoelectric ceramic in the radial polarization zone to form a first radial polarization zone and a second radial polarization zone of equal size; The annular piezoelectric ceramic is aged and subjected to high and low temperature cycle treatment to obtain a first radial polarization region, a second radial polarization region and an axial polarization region which are spaced apart from each other to form a piezoelectric element.

6. The method for manufacturing a piezoelectric element according to claim 5, characterized in that: The annular piezoelectric ceramic is aged at 3 / 5 of the Curie temperature of the piezoelectric ceramic for 48-96 hours, and is cycled between a low temperature of -65 to -55°C and a high temperature of 120 to 150°C for 10 to 20 cycles to obtain the desired piezoelectric element.

7. A sensor assembly, characterized in that: The sensor assembly comprises: A ceramic element, wherein the ceramic element is a piezoelectric element composed of a first radial polarization region, a second radial polarization region, and an axial polarization region as described in any one of claims 1 to 4, which are spaced apart from each other; A base, for mounting the ceramic element on the base; A mass block, located outside the ceramic element and used to limit the position of the ceramic element; and The fixing part is located outside the mass block and is used to fix the mass block and the ceramic element on the base.

8. The sensor assembly according to claim 7, characterized in that The fixing piece is a memory metal ring or a clamping ring.

9. The sensor assembly according to claim 7, characterized in that: The sensor assembly is a three-axis piezoelectric acceleration sensor, one of the three axes of the three-axis piezoelectric acceleration sensor is parallel to the polar axis direction of the axial polarization zone of the piezoelectric element, and one of the other two axes of the three-axis piezoelectric acceleration sensor is aligned with the center line of electrode block 2 between the first radial polarization zone and the second radial polarization zone of the piezoelectric element.

10. An electronic device, characterized in that: The electronic device comprises: The sensor assembly according to any one of claims 7 to 9.

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