KR20210048905A - Accelerometer and acoustic vector sensor having the same - Google Patents

Abstract

The present invention discloses an acceleration sensor, comprising: a base extending in one direction; a first piezoelectric element portion and a second piezoelectric element portion made of a piezoelectric element, and each formed to be in contact with one surface and the other surface of the base and supported by the base; and a first electrode and a second electrode each formed to be in contact with the other surface of the first and second piezoelectric elements, and disposed to face each other at least a portion thereof, wherein the first and second electrode sides are fixed, and the base side becomes a free end.

Description

Acceleration sensor and acoustic vector sensor having the same TECHNICAL FIELD [ACCELEROMETER AND ACOUSTIC VECTOR SENSOR HAVING THE SAME}

The present invention relates to an acceleration sensor using the piezoelectric effect of a piezoelectric element and an acoustic vector sensor having the same.

The towed array used in the ship is designed to have an omni-directional beam pattern by arranging several acoustic pressure hydrophone sensors linearly in order to obtain underwater acoustic signal information. Therefore, a linear towing sensor composed of a hydrophone exhibits an axisymmetric beam pattern.

Because of this axisymmetric beam pattern, it has a performance that cannot distinguish a target signal coming from the left or the right. In order to solve the problem of the left and right classification, the development of a pre-array towing sensor composed of a vector sensor may be considered.

Meanwhile, the vector sensor can provide directivity information in contrast to the conventional pressure-sensitive hydrophone by measuring the particle velocity of the sound wave. These vector sensors are classified into acceleration sensor-based inertial sensors and pressure-gradient sensors according to the basic principles implemented.

The inertial sensor measures the vibration of the housing induced by the motion of the sound wave particles with an acceleration sensor installed therein, and combines the non-directional hydrophone signal to measure the directional information of the sound wave. The vector sensor based on the inertial sensor requires a lightweight design in order to move sensitively to the motion of particles in the medium, and to measure the sound pressure at the same position as the hydrophone signal, the compact design of the hydrophone and the acceleration sensor and these It is important to organize with packaging. In addition, there is a requirement that the housing must be freely supported in order to sensitively respond to the motion of particles of a medium in an acoustic field without interference from the supporting structure.

The pressure change rate sensor obtains directivity information by using the time difference between the pressures measured at two points, and since the accuracy decreases when the distance is narrowed, the distance between the two points is important for performance and it is difficult to miniaturize.

An object of the present invention is to provide an acceleration sensor capable of further improving detection performance while having a relatively simple structure capable of miniaturization and weight reduction, and an acoustic vector sensor having the same inside a hydrophone capable of omnidirectional sound wave detection. have.

In order to achieve the object of the present invention, the acceleration sensor includes a base extending in one direction; A first piezoelectric element portion and a second piezoelectric element portion formed of a piezoelectric element, each of which is formed to contact one surface and the other surface of the base and supported by the base; And a first electrode and a second electrode formed to contact the other surfaces of the first and second piezoelectric elements, respectively, and at least partially facing each other, wherein the first and second electrode sides are fixed, and the base The side becomes the free end.

The vibration direction of the first and second piezoelectric element portions is, the electric field is formed in a first direction in which the first and second electrodes face each other, and the deformation is in a second direction in which the first and second piezoelectric element portions extend. Can be formed.

The base may be formed such that a cross-sectional area decreases toward one end where the free end is formed.

The piezoelectric element may be made of a piezoelectric single crystal material polarized in the [011] direction.

The piezoelectric single crystal material may include at least one of PMN-PT, PIN-PMN-PT, PIN-PMN-PT Mn dopped, PMN-PZT, and PMN-PZT Mn dopped.

The acceleration sensor may further include a weight portion coupled to one end portion at which the free end is formed in the base.

The base may include an exposed portion protruding from the first and second piezoelectric element portions at one end portion where the free end is formed, and the weight portion may be formed to surround at least a portion of the exposed portion.

On the other hand, in order to achieve the object of the present invention, the acceleration sensor; And a hydrophone having a hollow portion and accommodating the acceleration sensor in the hollow portion.

The acceleration sensor may include a first acceleration sensor and a second acceleration sensor, each of which has the free ends facing each other, and the first acceleration sensor and the second acceleration sensor may be configured such that vibration directions cross each other. have.

The first and second acceleration sensors may be disposed such that vibration directions are perpendicular to each other.

The hydrophone is formed to extend in one direction and has openings at both ends, and the acoustic vector sensor is coupled to the opening to close both ends of the hydrophone, and the first electrode and the second electrode are Each of the one end portion may further include an end cap portion for fixing the side of the first and second electrode.

On the other hand, in order to achieve the object of the present invention, a hydrophone having a hollow portion; And a piezoelectric element, wherein one end is fixed in the hollow part of the hydrophone, and the other end is arranged to face each other in a free state, and the other end facing each other is vibrated by the transmitted acoustic wave. Including a first acceleration sensor and a second acceleration sensor configured to be configured, the first and second acceleration sensors, propose an acoustic vector sensor disposed so that the vibration directions cross each other.

The first and second acceleration sensors may be disposed such that vibration directions are perpendicular to each other.

The effects of the present invention obtained through the above-described solution are as follows.

The acceleration sensor of the present invention has a relatively simple structure consisting of a base, a first piezoelectric element portion and a second piezoelectric element portion, and a first electrode and a second electrode, and thus it is easy to manufacture and use.

In addition, since the acceleration sensor has a cantilevered structure, it is possible to make a vibrating body of low rigidity, and if it has the same resonance frequency, it is possible to reduce the size/weight of the acceleration sensor. In addition, the application of a piezoelectric single crystal material polarized in the [011] direction having a high piezoelectric constant with respect to the vibration direction can have high sensitivity. The cantilever structure can maximize the amount of deformation of the first and second piezoelectric elements, and a weight portion is coupled to one end of the base to further improve sensing performance.

In addition, the first acceleration sensor and the second acceleration sensor of the present invention have a piezoelectric constant of 0 (zero) at an angle other than the vibration direction, so that sound waves can be detected in the directions installed in each of them. An acoustic vector sensor capable of detecting two-axis acoustics may be implemented by synthesizing the hydrophone signal and the first and second acceleration sensor signals.

1 is a perspective view showing an acceleration sensor and an acoustic vector sensor having the same according to an embodiment of the present invention.
2 is a perspective view showing one of the acceleration sensors shown in FIG. 1 separated.
3 is a perspective view showing a form in which a weight part is excluded from the acceleration sensor shown in FIG. 2.
4A and 4B are conceptual diagrams for explaining mechanical deformation occurring in the acceleration sensor shown in FIG. 3.

Hereinafter, an acceleration sensor and an acoustic vector sensor having the same according to the present invention will be described in more detail with reference to the drawings. In this specification, the same/similar reference numerals are assigned to the same/similar configurations even in different embodiments, and the description will be replaced with the first description. Singular expressions used in the present specification include plural expressions unless the context clearly indicates otherwise.

1 is a perspective view showing an acceleration sensor 100 and an acoustic vector sensor 10 having the same according to an embodiment of the present invention.

Referring to FIG. 1, the acoustic vector sensor 10 includes a hydrophone 11 and an acceleration sensor 100.

The hydrophone 11 may include a hollow portion 11a for accommodating an acceleration sensor 100 to be described later, and may have a cylindrical shape extending in one direction as shown in FIG. 1.

The hydrophone 11 may include a hollow portion 11a for accommodating an acceleration sensor 100 to be described later, and may have a spherical shape. In addition, the hydrophone 11 may have a cylindrical structure having openings O at both ends.

The hydrophone 11 is a piezoelectric element and may be made of a piezoelectric ceramic material of a PZT series or a piezoelectric single crystal material such as PMN-PT.

The hydrophone 11 has an omni-directional beam pattern capable of measuring equal sound pressure in all directions.

The acceleration sensor 100 includes a piezoelectric element, and in the hollow portion 11a provided in the hydrophone 11, one end is fixed and the other end is disposed in a free state. That is, the acceleration sensor 100 is configured to have a cantilever structure in which a free end is formed at the other end. Here, the acceleration sensor 100 is configured to cause vibration at the other end where the free end is formed by an acoustic wave transmitted from the outside.

The piezoelectric element has a piezoelectric effect, that is, a voltage is generated when a mechanical pressure is applied, and a mechanical deformation occurs when a voltage is applied. When an external force is applied, electric polarization occurs, resulting in a potential difference. It refers to a device that has the property of generating deformation. The acceleration sensor 100 is configured to measure acceleration with respect to an acoustic wave by using the characteristics of the piezoelectric element.

In addition, the acceleration sensor 100 may be composed of a single number or a plurality of units. For example, as shown in FIG. 1, the acceleration sensor 100 may include a first acceleration sensor 100a and a second acceleration sensor 100b having the same structure. Here, the first acceleration sensor 100a and the second acceleration sensor 100b face each other with one end fixed and the other end formed in the hollow part 11a of the hydrophone 11, respectively. Can be arranged to see. In addition, the first and second acceleration sensors 100a and 100b may be disposed so that the vibration directions cross each other. For example, the first and second acceleration sensors 100a and 100b may be disposed so that directions of vibrations generated by acoustic waves are perpendicular to each other.

Meanwhile, the hydrophone 11 may extend in one direction as shown in FIG. 1 and may have openings O communicating with the hollow part 11a at both ends. In addition, the acoustic vector sensor 10 may further include an end cap part 13.

The end cap part 13 is coupled to the opening O provided in the hydrophone 11 to close both ends of the hydrophone 11, and the first acceleration sensor 100a and the first 2 It may be coupled to one end of the acceleration sensor 100b to form a fixed end of the first and second acceleration sensors 100a and 100b having a cantilevered structure. The end cap part 13 may include a first end cap 13a disposed on the side of the first acceleration sensor 100a and a second end cap 13b disposed on the side of the second acceleration sensor 100b. have. The end cap part 13 may be formed of a polymer material of a low specific gravity material so that the acoustic vector sensor 10 can stably operate in water.

Hereinafter, the acceleration sensor 100 of the present invention will be described in more detail with reference to FIGS. 2, 4A and 4B.

FIG. 2 is a perspective view showing one of the acceleration sensors 100 shown in FIG. 1 separated, and FIG. 3 is a perspective view showing a form in which the weight part 140 is removed from the acceleration sensor 100a shown in FIG. 2, 4A and 4B are conceptual diagrams for explaining mechanical deformation occurring in the acceleration sensor 100 shown in FIG. 3.

4A to 4B, the acceleration sensor 100 includes a base 110, a first piezoelectric element part 121, a first electrode 131 and a second electrode 132.

The base 110 is formed to extend in one direction as shown in FIG. 1. For example, the base 110 may be formed in a plate shape having a predetermined thickness, such as a strap shape.

The first piezoelectric element portion 121 and the second piezoelectric element portion 122 are made of a piezoelectric element, and each one surface thereof is formed to contact one surface and the other surface of the base 110. ) Supported by As described above, the piezoelectric element refers to a device having a property of causing electric polarization to occur when an external force is applied to generate a potential difference, and to generate deformation or deformation when a voltage is applied on the contrary. In addition, the piezoelectric element may be made of a piezoelectric single crystal material polarized in the [011] direction. Here, the piezoelectric single crystal material may include at least one of PMN-PT, PIN-PMN-PT, PIN-PMN-PT Mn dopped, PMN-PZT, and PMN-PZT Mn dopped. Here, the [011] direction means a crystal structure direction of the piezoelectric single crystal material in the direction Z in which an electric potential is formed in the electrode. As shown in FIG. 4B, compression and tensile deformation occurs in the first piezoelectric element part 121 and the second piezoelectric element part 122 respectively in one direction by the deformation of the cantilever structure, and the piezoelectric polarized in the [001] direction. The single crystal material is characterized by having high piezoelectric properties against such deformation in the longitudinal direction.

More specifically, the deformation direction of the first and second piezoelectric element portions 121 and 122 due to vibration is shown in the second direction in which the first and second piezoelectric element portions 121 and 122 extend, that is, FIGS. 2 to 4B. It may be formed in the Y-axis direction, and the direction of the electric field is formed in the first direction in which the first and second electrodes 131 and 132 face each other, that is, in the Z-axis direction shown in FIGS. 2 to 4B. The vibration and electric field directions of the first and second piezoelectric element portions 121 and 122 may be expressed in the [32] direction.

On the other hand, as in the present invention, when the vibration direction is used in the [32] direction, the use of a _{piezoelectric single crystal material having a high elastic compliance coefficient (s 22} ) in two directions representing strain versus stress reduces the stiffness of the cantilever to the overall acceleration sensor You can reduce the mass.

As described above, when the piezoelectric single crystal material is polarized in the [011] direction, the piezoelectric single crystal material has a very high d32 (630 ~ 2750 pC/N) value and can be sensitive to high sensitivity. In addition, since the size of _{s 22 is also more than twice as large as the value of s 33} , the structure of the present invention can be made compact/lightweight.

The first electrode 131 and the second electrode 132 are respectively disposed on the other surfaces of the first piezoelectric element portion 131 and the second piezoelectric element portion 132, that is, the first and second piezoelectric element portions ( 121 and 122 are formed to contact the other surfaces of the first and second piezoelectric element portions 121 and 122, which are opposite surfaces of one surface in contact with the base 110, and at least some are disposed to face each other. For example, the first and second electrodes 131 and 132 may be formed to protrude from the ends of the first and second pressure contacting device parts 121 and 122, and contact the first and second piezoelectric device parts 121 and 122. One surface of the first and second piezoelectric element portions 121 and 122 may be formed to protrude from ends of the first and second piezoelectric element portions 121 and 122 so that portions not in contact with the first and second piezoelectric element portions 121 and 122 face each other. In addition, the first and second electrodes 131 and 132 may be formed through a known electrode treatment method, such as plating a metal material having high strength with gold.

Here, the acceleration sensor 100 may be configured such that the first and second electrodes 131 and 132 sides are fixed, and the base 110 side is a free end. In addition, the base 110 may be formed to have a reduced cross-sectional area toward one end where the free end is formed. For example, the base 110 may be formed in a plate shape having a trapezoidal shape, as shown in FIG. 3. According to such a structure, the amount of vibration generated at one end of the base 110 can be maximized. In addition, the base 110 not only supports the first and second pressure contacting device portions 121 and 122, but also serves as a ground electrode as shown in FIGS. 4A and 4B. Accordingly, the base 110 may be selected from various materials capable of performing this function, but is preferably made of a steel material. In addition, in the case of the first and second pressure bonding element portions 121 and 122, it is preferable that they are formed in a strap shape having a predetermined thickness, like the base 110.

In addition, the first and second electrodes 131 and 132 are coupled to the end cap portion 13 described above with reference to FIG. 1 at one end, respectively, and fix the sides of the first and second electrodes 131 and 132 to have a cantilever structure. A fixed end of the acceleration sensor 100 may be formed. In addition, when describing the first end cap 13a among the end cap parts 13 as an example, the first end cap 13a may be composed of a first part 13a' and a second part 13a". In addition, the first and second portions 13a ′ and 13a ″ may be coupled to each other to fix the sides of the first and second electrodes 131 and 132.

On the other hand, the deformation direction by the vibration of the first and second piezoelectric element portions 121 and 122 is a second direction in which the first and second piezoelectric element portions 121 and 122 extend, that is, Y shown in FIGS. 2 to 4B. It may be formed in an axial direction, and the direction of the electric field is formed in a first direction in which the first and second electrodes 131 and 132 face each other, that is, in the Z-axis direction shown in FIGS. 2 to 4B. The vibration and electric field directions of the first and second piezoelectric element portions 121 and 122 may be expressed in the [32] direction.

In addition, the acceleration sensor 100 may further include a weight part 140. When the first acceleration sensor 100a illustrated in FIG. 2 is described as an example, the weight part 140 may be coupled to one end of the base 110 at which the free end is formed. In addition, the base 110 may include an exposed portion 110a protruding from the first and second piezoelectric element portions 121 and 122 at one end portion where the free end is formed, and in this case, the weight portion ( 140 may be formed to surround at least a portion of the exposed portion 110a formed on the base 110. The weight part 140 may be formed of a material having a relatively high density, such as tungsten. By the configuration of the weight part 140, it is disposed at the free end of the acceleration sensor 100, and the vibration of the first and second piezoelectric element parts 121 and 122 can be further amplified, thereby improving sensitivity. The vibration here is the vibration of the acceleration sensor 100 itself, and when the vibration of the weight is amplified, the amount of deformation of the first and second piezoelectric elements 121 and 122 also increases. In addition, the weight part 140 may include a first weight member 141 and a second weight member 142 formed to cover one surface and the other surface of the base 110, respectively.

In addition, the acceleration sensor 100 may further include a resin part 150. When described with reference to the first acceleration sensor 100a shown in FIG. 2, the resin part 150 is formed in a space spaced apart from the first and second weight members 141 and 142 and the base 110 to be The first and second weight members 141 and 142 may be stably fixed on (110). The resin part 150 may be made of, for example, epoxy.

According to the above description, the acceleration sensor 100 and the acoustic vector sensor 10 having the same include the polarization directions of the first and second piezoelectric elements 121 and 122 and the arrangement of the first and second electrodes 131 and 132, As the acceleration sensor 100 is formed in a cantilever shape in consideration of the vibration directions of the first and second piezoelectric elements 121 and 122, since interference between the acceleration sensors 100 does not occur, a single package Detection is possible. In addition, it is possible to implement an acoustic vector sensor 10 inserted into the hollow hydrophone 11 by using the structure of the acceleration sensor 100 capable of miniaturization and weight reduction, which is the acoustic detection position of the acceleration sensor and the sound of the hydrophone. It has the effect of increasing the measurement accuracy by making the detection location the same.

The above description is merely exemplary, and various modifications may be made by those of ordinary skill in the technical field to which the present invention pertains, without departing from the scope and technical spirit of the described embodiments. The above-described embodiments may be implemented individually or in any combination.

100: acceleration sensor 110: base
110a: exposed portion 121: first piezoelectric element portion
122: second piezoelectric element part 131: first electrode
132: second electrode 140: parts by weight
141: first weight member 142: second weight member
150: resin part 10: acoustic vector sensor
11: hydrophone 11a: hollow part
13: end cap portion 13a: first end cap
13b: second end cap

Claims (13)

A base extending in one direction;
A first piezoelectric element portion and a second piezoelectric element portion formed of a piezoelectric element, each of which is formed to contact one surface and the other surface of the base and supported by the base; And
Each includes a first electrode and a second electrode formed to contact the other surfaces of the first and second piezoelectric elements, and at least partially disposed to face each other,
The first and second electrode sides are fixed, and the base side is an acceleration sensor having a free end. The method of claim 1,
The vibration direction of the first and second piezoelectric element portions is formed in a first direction in which the first and second electrodes face each other, and the deformation is in a second direction in which the first and second piezoelectric element portions extend. Acceleration sensor formed. The method of claim 1,
The base is an acceleration sensor that is formed such that a cross-sectional area decreases toward one end where the free end is formed. The method of claim 1,
The acceleration sensor made of a piezoelectric single crystal material in which the piezoelectric element is polarized in the [011] direction. The method of claim 4,
The piezoelectric single crystal material is an acceleration sensor comprising at least one of PMN-PT, PIN-PMN-PT, PIN-PMN-PT Mn dopped, PMN-PZT and PMN-PZT Mn dopped. The method of claim 1,
Acceleration sensor further comprising a weight portion coupled to one end portion of the free end is formed in the base. The method of claim 6,
The base includes an exposed portion protruding from the first and second piezoelectric element portions at one end portion where the free end is formed,
The acceleration sensor is formed so as to surround at least a portion of the weight portion of the exposed portion. The acceleration sensor according to any one of claims 1 to 7; And
An acoustic vector sensor comprising a hydrophone having a hollow portion and accommodating the acceleration sensor in the hollow portion. The method of claim 8,
The acceleration sensor includes a first acceleration sensor and a second acceleration sensor, wherein each of the free ends is disposed to face each other,
The first acceleration sensor and the second acceleration sensor are acoustic vector sensors such that vibration directions cross each other. The method of claim 9,
The first and second acceleration sensors are acoustic vector sensors disposed so that vibration directions are perpendicular to each other. The method of claim 8,
The hydrophone is formed extending in one direction and has openings at both ends,
It is coupled to the opening and formed to close both ends of the hydrophone, and is coupled to one end of the first electrode and the second electrode, respectively, further comprising an end cap portion for fixing the side of the first and second electrodes Acoustic vector sensor. Hydrophone having a hollow portion; And
A piezoelectric element is provided, and in the hollow part of the hydrophone, one end is fixed and the other end is arranged to face each other in a free state, and the other end facing each other is vibrated by the transmitted acoustic wave. Including a configured first acceleration sensor and a second acceleration sensor,
The first and second acceleration sensors are acoustic vector sensors disposed such that vibration directions cross each other. The method of claim 12,
The first and second acceleration sensors are acoustic vector sensors disposed so that vibration directions are perpendicular to each other.

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