KR20170078382A - Acceleration Sensor - Google Patents

Acceleration Sensor Download PDF

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Publication number
KR20170078382A
KR20170078382A KR1020150188842A KR20150188842A KR20170078382A KR 20170078382 A KR20170078382 A KR 20170078382A KR 1020150188842 A KR1020150188842 A KR 1020150188842A KR 20150188842 A KR20150188842 A KR 20150188842A KR 20170078382 A KR20170078382 A KR 20170078382A
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KR
South Korea
Prior art keywords
piezoelectric
pmn
acceleration sensor
partition
attached
Prior art date
Application number
KR1020150188842A
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Korean (ko)
Inventor
이정호
권명주
이상구
Original Assignee
(주)아이블포토닉스
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Application filed by (주)아이블포토닉스 filed Critical (주)아이블포토닉스
Priority to KR1020150188842A priority Critical patent/KR20170078382A/en
Publication of KR20170078382A publication Critical patent/KR20170078382A/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/09—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/16—Receiving elements for seismic signals; Arrangements or adaptations of receiving elements
    • G01V1/18—Receiving elements, e.g. seismometer, geophone or torque detectors, for localised single point measurements
    • G01V1/186—Hydrophones

Abstract

According to the present invention, there is provided a hollow cylindrical base in which a first space and a second space are formed by being partitioned by a partition wall; A first piezoelectric part disposed on a first side of the partition wall, wherein an insulator having an electrode layer formed is attached to at least one surface of the first PMN-PT piezoelectric element; A first mass attached to the first piezoelectric portion on the opposite side of the partition; A second piezoelectric part disposed on a second side of the partition wall, the second piezoelectric part having an insulator with an electrode layer attached to at least one surface of the second PMN-PT piezoelectric element; And a second mass attached to the second piezoelectric part on the opposite side of the partition wall, and a hydrophone including the acceleration sensor.

Description

Acceleration Sensor

The present invention relates to an acceleration sensor, and more particularly, to an acceleration sensor using a piezoelectric single crystal and a hydrophone having the acceleration sensor.

The acceleration sensor processes the output signal to measure dynamic forces such as acceleration, vibration, and shock of the object. The acceleration sensor is used in various fields, for example, in a control system of a transportation means, a factory automation and a robot, and is also incorporated in a communication device. If the acceleration sensor is classified into the detection method, it can be classified into inertia type, gyro type, and silicon semiconductor type.

The inertial acceleration sensor includes an acceleration sensor using a piezoelectric material. An example of a piezoelectric material widely used at present is lead zirconate titanate (PZT) ceramics. The acceleration sensor using the PZT ceramics has been improved for a long time, but it is difficult to further improve the performance due to the limitation of the piezoelectric material itself.

To solve this problem, an alternative using a PMN-PT single crystal as a piezoelectric material has been proposed. PZT ceramics are made of irregular particles, whereas PMN-PT single crystals have a structure in which fine particles having a certain structure are regularly arranged. The PMN-PT single crystal exhibits excellent physical properties as compared with PZT ceramics, and therefore performance improvement can be achieved when used as a piezoelectric material in an acceleration sensor.

Specifically, the PMN-PT single crystal is a solid solution single crystal of magnesium niobate (PMN), which is a relaxor, and titanic acid lead (PT), which is a piezoelectric material. When a PMN-PT single crystal is used as a piezoelectric material in an acceleration sensor, the piezoelectric distortion is three times or more larger than that of a conventional piezoelectric material of PZT ceramics, the electromechanical coupling coefficient is large, .

On the other hand, a hydrophone is an accelerometer for use in an ocean search, and has an accelerometer composed of a piezoelectric material. In a hydrophone, the force of a sound wave is transmitted to a rigid body constituting the base of the accelerometer, whereby the accelerometer senses the pressure, and the direction of the sound wave can be detected from the electrical signal.

U.S. Patent No. 7,066,026 B2 discloses an accelerometer using a PMN-PT single crystal and an acoustic vector sensor having the accelerometer. The accelerometer disclosed in the above-mentioned United States patent discloses a structure in which a piezoelectric material composed of a PMT-PT single crystal is disposed between a mass and a base, and a cast pattern (a protrusion and a recess) is formed between the piezoelectric material and the mass, castellated pattern to reduce the negative effect on the relaxor crystal.

On the other hand, the acoustical vector sensor disclosed in the U.S. patent includes three accelerometers disposed on the inner circumference of the cylindrical housing. Each of the piezoelectric materials included in each of the accelerometers is cut in a specific orientation so as to generate a maximum piezoelectric response in the first direction, In the second direction and the third direction, which are the first and second directions. Therefore, the three accelerometers provided in the acoustic vector sensor are installed inside the cylindrical housing so that the orientations of the respective piezoelectric materials are orthogonal to each other, and the direction of the sound wave can be determined from the different signals detected from the three accelerometers have.

The accelerometer disclosed in the U.S. patent shows superior performance to an accelerometer using a PZT piezoelectric material by using a PMN-PT single crystal as a piezoelectric material. However, when used in an acoustic vector sensor or the like, two or more accelerometers must be included, and it is not easy to install the accelerometer in the cylindrical housing of the acoustic vector sensor disclosed in the U.S. patent.

It is an object of the present invention to provide an improved acceleration sensor and a hydrophone including the same.

Another object of the present invention is to provide an acceleration sensor using a PMN-PT single crystal and a hydrophone including the acceleration sensor.

It is another object of the present invention to provide an acceleration sensor capable of detecting acceleration in more than one direction and a hydrophone capable of detecting sound waves in more than one direction.

In order to achieve the above object, according to the present invention,

A hollow cylindrical base in which a first space and a second space are formed by being partitioned by the partition wall;

And an insulator having an electrode layer formed on at least one surface of the first PMN-PT piezoelectric body, the first piezoelectric portion being disposed on a first side of the partition wall, A first piezoelectric part;

A first mass attached to the first piezoelectric portion on the opposite side of the partition;

A second piezoelectric part disposed on a second side of the partition wall, the second piezoelectric part having an insulator with an electrode layer attached to at least one surface of the second PMN-PT piezoelectric element; And

And a second mass body attached to the second piezoelectric part on an opposite side of the partition wall.

According to one aspect of the present invention, the first and second PMN-PT piezoelectric elements are arranged such that the direction in which the maximum piezoelectric response of the first PMN-PT piezoelectric body is obtained and the direction in which the maximum piezoelectric response of the second PMN- 2 piezoelectric part is disposed on the partition wall.

According to another aspect of the present invention, the insulator is attached to both surfaces of the first PMN-PT piezoelectric body, and the insulator is attached to both surfaces of the second PMN-PT piezoelectric body.

According to another aspect of the present invention, holes are formed in the partition walls symmetrically with respect to the center of the partition walls.

According to another aspect of the present invention, the holes are arranged so as not to interfere with the first piezoelectric portion and the second piezoelectric portion.

According to another aspect of the present invention, there is provided an acceleration sensor comprising: And cylindrical hydrophone rings disposed at both side ends of the hollow cylindrical base.

According to another aspect of the present invention, the outer cylindrical surface of the hollow cylindrical base and the cylindrical hydrophone ring of the acceleration sensor is surrounded by a molding.

According to another aspect of the invention, a decoupling ring is disposed between the end of the hollow cylindrical base and the cylindrical hydrophone ring for decoupling the movement of the cylindrical hydrophone ring relative to the acceleration sensor.

The acceleration sensor and the hydrophone according to the present invention can improve the sensing performance by using the PMN-PT single crystal as the piezoelectric material. Also, since it has a simple structure, it is easy to manufacture and easy to handle.

1 is an exploded perspective view of an acceleration sensor according to an embodiment of the present invention.
FIG. 2 is a sectional view, a right side view, and a left side view of the acceleration sensor according to the present invention shown in FIG. 1;
3 is a cross-sectional view of a hydrophone according to the present invention with the acceleration sensor shown in Figs. 1 and 2. Fig.

FIG. 1 is a schematic exploded perspective view of an acceleration sensor according to the present invention, and FIG. 2 is a sectional view, a right side view and a left side view of the acceleration sensor according to the present invention shown in FIG.

Referring to the drawings, an acceleration sensor according to the present invention includes a hollow cylindrical base 10 having a first space 10a and a second space 10b formed therein by being divided by a partition 11; A first PMN-PT piezoelectric body 22 having insulators 23a and 23b attached to both surfaces thereof is disposed on the partition 11 in the first space 10a, A first piezoelectric part (21); A first mass body (24) attached to the first piezoelectric part (21) on the opposite side of the partition (11); The second piezoelectric portion 31 disposed on the partition 11 in the second space 10b includes a second PMN-PT piezoelectric body 32 having insulators 33a and 33b on both surfaces thereof A second piezoelectric part 31; And a second mass body (34) attached to the second piezoelectric part (31) on the opposite side of the partition (11).

The base 10 may preferably be cylindrical. The cylindrical base 10 is formed into a hollow cylindrical shape with both side ends opened as a whole. The cylindrical base 10 has a partition 11 and a circumferential wall 12 located in the middle of the cylinder as shown in Fig. The inner space of the cylindrical base 10 is divided into the first space 10a and the second space 10b by the partition 11 and the first space and the second space may have a cylindrical shape.

It is preferable that one or more holes 11a are formed in the partition 11. In the example shown in the drawing, the four holes 11a are symmetrically formed with respect to the center of the circular partition 11. It is preferable that each of the four holes 11a is formed so as not to interfere with the first piezoelectric portion 21 and the second piezoelectric portion 31 disposed in the partition 11. [ That is, it is preferable that the holes 11a are formed so as not to be blocked by the first and second PMN-PT piezoelectric elements 22 and 32. The holes 11a serve as through holes for the electric cables to be connected to the electrodes of the first PMN-PT piezoelectric body 22 and the second PMN-PT piezoelectric body 32, and simultaneously reduce the weight of the cylindrical base 10 . The cylindrical base 10 is preferably made of aluminum.

The first PMN-PT piezoelectric element 22 and the second PMN-PT piezoelectric element 32 are not particularly limited and include electromechanical coupling factors k31 and k33 and piezoelectric constant d31, d33), and the like. Specifically, PMN-PT, PZN-PT (PZNT) and the like are exemplified, and preferably PMN-PT piezoelectric single crystal is formed. Hereinafter, PMN-PT piezoelectric single crystal will be described as an example.

As shown in the figure, the first PMN-PT piezoelectric body 22 and the second PMN-PT piezoelectric body 32 have a rectangular parallelepiped shape and are formed as a thin rectangular plate.

Each of the first PMN-PT piezoelectric body 22 and the second PMN-PT piezoelectric body 32 generates a maximum piezoelectric response in the first direction, while the second PMN-PT piezoelectric body 22 generates the maximum piezoelectric response in the first direction, Lt; RTI ID = 0.0 > a < / RTI > minimum piezoelectric response. For example, if the width direction of the PNN-PT piezoelectric element formed in a rectangular parallelepiped corresponds to the first direction for generating the maximum piezoelectric response, a minimum piezoelectric response is generated in both the width direction and the thickness direction perpendicular to the longitudinal direction.

Thus, if the first PMN-PT piezoelectric element 22 and the second PMN-PT piezoelectric element 32 all have the same shape and have the same orientation, the first PMN-PT piezoelectric element 22 and the second PMN- 32 are arranged at right angles to each other so that the direction in which the first PMN-PT piezoelectric element 22 generates the maximum piezoelectric response and the direction in which the second PMN-PT piezoelectric element 32 generates the maximum piezoelectric response are orthogonal to each other . For example, in the X-Y-Z coordinate system, the first PMN-PT piezoelectric element 22 has the maximum piezoelectric response in the Z direction, while minimizing the piezoelectric response in the X and Y directions. In addition, the second PMN-PT piezoelectric element 32 has the maximum piezoelectric response in the Y direction, while minimizing the piezoelectric response in the X and Z directions. Typically, the maximum piezoelectric response is measured to be twice the minimum piezoelectric response, and this difference can be used to detect the direction of the sound waves.

The most preferred piezoelectric single crystal to be applied to the acceleration sensor of the present invention may be the <011> mode. The < 011 > mode shows a characteristic in which the difference in strength between the y-axis and the z-axis is 10 times or more. More specifically, it is most preferable to use the d15 mode for the z-axis and the d16 mode for the y-axis. However, the present invention is not limited thereto.

In the example shown in the figure, the length L of the first PMN-PT piezoelectric element 22 and the length L of the second PMN-PT piezoelectric element 32 are arranged to be perpendicular to each other, It can be understood that the mass body 24 and the second mass body 34 are also disposed at right angles to each other.

Insulators 23a and 23b are attached to both side surfaces of the first PMN-PT piezoelectric element 22, respectively. Similarly, insulators 33a and 33b are attached to both side surfaces of the second PMN-PT piezoelectric body 32, respectively. The insulator can be used without limitations as long as it is a non-conductive material, and may preferably be formed of alumina.

An electrode layer is formed on the surface where the insulators 23a and 23b are bonded to the PMN-PT piezoelectric body by sputtering a conductive metal. The kind of the conductive metal is not particularly limited. The electrode layer forming method is not limited to sputtering, and any technique known in the related art is applicable without limitation.

The insulator serves to minimize or reduce the noise of the voltage sensed by the acceleration sensor, and the electrode layer formed on the insulator serves to extract the signal of the acceleration sensor. The insulator and the piezoelectric body may be mutually bonded using an epoxy, but are not limited thereto. Specifically, when an electrode layer formed on an insulator is disposed so as to face the piezoelectric body, the piezoelectric body and the electrode layer are bonded to each other in a conductive state by bonding using epoxy and curing at a temperature of 60 degrees Celsius.

It is preferable that the area of the insulator having the electrode layer formed is set larger than the area of the piezoelectric body. More specifically, it is more preferable that the width of the insulator having the electrode layer formed is larger than the width of the piezoelectric body. By doing so, a part of the electrode layer formed on the insulator protrudes beyond the edge of the piezoelectric body, and a wire can be connected to the electrode layer of the protruding insulator with silver epoxy or the like. In this way, insulators 23a and 23b are coupled to both surfaces of the first PMN-PT piezoelectric body 22, and wires can be connected to the insulators 23a and 23b. Likewise, insulators 33a and 33b are coupled to both surfaces of the second PMN-PT piezoelectric body 32, and wires can be connected to the insulators 33a and 33b. By having such a configuration, a terminal board for connecting wires (signal lines) becomes unnecessary.

The first mass body 24 is attached to the first piezoelectric part 21 so that the first PMN-PT piezoelectric body 22 is disposed between the partition 11 of the cylindrical base 10 and the first mass body 24 . Similarly, the second mass body 34 is attached to the second piezoelectric portion 31 so that the second PMN-PT piezoelectric body 32 is sandwiched between the partition 11 and the second mass body 34 of the cylindrical base 10 . The first mass body 12 and the second mass body 14 may be made of a general SUS material.

2, the first piezoelectric part 21 and the first mass body 24 are installed inside the first space 10a and are installed so as not to block the hole 11a formed in the partition 11 . Similarly, the second piezoelectric portion 31 and the mass body 34 are included in the second space 10b and are installed so as not to block the hole 11a formed in the partition 11. The length of the first PMN-PT piezoelectric body 21 having a rectangular shape is set to be perpendicular to the length of the second PMN-PT piezoelectric body 31, as shown in the figure. The length of the first mass body 24 having a rectangular shape is set to be perpendicular to the length of the second mass body 34.

The joining of the partition 11 of the cylindrical base 10, the first PMN-PT piezoelectric body 21, the first mass body 24, the first PMN-PT piezoelectric body 32 and the second mass body 34 is performed using an adhesive . For example, epoxy adhesives can be used, especially Epo-Tek 301 epoxy adhesives. After the adhesive is applied to the attachment surface by spreading it thinly, the respective components are joined and then bonded at a high temperature (about 60 DEG C) for about one hour.

FIG. 3 is a cross-sectional view of a schematic structure of a hydrophone according to the present invention having the acceleration sensor shown in FIGS. 1 and 2.

Referring to the drawings, a hydrophone according to the present invention includes cylindrical hydrophone rings 51 and 52 disposed at both ends of a cylindrical base 10 of an acceleration sensor 1, The outer surface of the cylindrical base 10 and the cylindrical hydrophone rings 51, 52 is wrapped by a molding 54. The diameter of each of the hydrophone rings 51 and 52 is the same as the diameter of the cylindrical base 10.

Between both ends of the cylindrical base 10 and the cylindrical hydrophone rings 51 and 52, a ring 55 for decoupling is arranged. The decoupling ring 55 is the same as corprene made of cork material and serves to decouple the motion of the hydrophone ring. That is, the decoupling ring 55 serves to decouple the movement of the hydrophone rings 51 and 52 from the acceleration sensor 1, and allows only sound waves and vibrations to be transmitted to the acceleration sensor 1 .

The acceleration sensor 1 included in the hydrophone according to the present invention includes a hollow cylindrical base 10 as described with reference to Fig. 1 and a partition wall 11 inside the hollow cylindrical base 10 The first piezoelectric unit 21 and the first mass unit 24 and the second piezoelectric unit 32 and the second mass unit 34 disposed in the first space 10a and the second space 10b, Respectively.

In the hydrophone constructed as described above, the hydrophone rings 51 and 52 detect sound waves or vibrations through the molding 54. When a force due to sound waves or vibration is applied, the first piezoelectric part 21 and the second piezoelectric part The piezoelectric actuator 31 outputs a piezoelectric response signal which is different from each other by being subjected to a shear force between the bulkhead 11 of the base 10 and the masses 24 and 34. Therefore, the direction of the sound wave can be detected by analyzing the different piezoelectric response signals.

That is, since the hydrophone rings are disposed on both sides of the acceleration sensor 1, the equilibrium state is established, and therefore, the sensor can be prevented from being tilted. When sound waves or vibrations are applied from the outside, PMN-PT monocrystals provided in the respective piezoelectric units twist between the bulkhead of the base and the masses to generate charges, thereby detecting different piezoelectric response signals. At this time, the ring for decoupling made of cork material decouples the motion of the hydrophone ring so that the piezoelectric sensor can more accurately detect sound waves or vibrations.

10. Base 21. First full-
22. First piezoelectric body 24. First mass body
31. Second piezoelectric part 32. Second piezoelectric element

Claims (8)

A hollow cylindrical base in which a first space and a second space are formed by being partitioned by the partition wall;
A first piezoelectric part disposed on a first side of the partition wall, wherein an insulator having an electrode layer formed is attached to at least one surface of the first PMN-PT piezoelectric element;
A first mass attached to the first piezoelectric portion on the opposite side of the partition;
A second piezoelectric part disposed on a second side of the partition wall, the second piezoelectric part having an insulator with an electrode layer attached to at least one surface of the second PMN-PT piezoelectric element; And
And a second mass attached to the second piezoelectric part on the opposite side of the partition wall. The method according to claim 1,
The first piezoelectric portion and the second piezoelectric portion are disposed on the partition wall so that the direction in which the maximum piezoelectric response of the first PMN-PT piezoelectric body is obtained and the direction in which the maximum piezoelectric response of the second PMN-PT piezoelectric body is obtained are orthogonal to each other And the acceleration sensor. The method according to claim 1,
Wherein the insulator is attached to both surfaces of the first PMN-PT piezoelectric body, and the insulator is attached to both surfaces of the second PMN-PT piezoelectric body, respectively. The method according to claim 1,
Wherein the partition is formed with holes symmetrically disposed in the center of the partition. 5. The method of claim 4,
And the holes are arranged so as not to interfere with the first piezoelectric portion and the second piezoelectric portion. An acceleration sensor according to any one of claims 1 to 5; And
And cylindrical hydrophone rings disposed at opposite ends of the hollow cylindrical base. The method according to claim 6,
Wherein the hollow cylindrical base of the acceleration sensor and the outer surface of the cylindrical hydrophone ring are surrounded by molding. The method according to claim 6,
Characterized in that a decoupling ring is disposed between the end of the hollow cylindrical base and the cylindrical hydrophone ring for decoupling the movement of the cylindrical hydrophone ring relative to the acceleration sensor.
KR1020150188842A 2015-12-29 2015-12-29 Acceleration Sensor KR20170078382A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019118966A1 (en) * 2017-12-15 2019-06-20 Pgs Geophysical As Seismic pressure and acceleration sensor
KR102170736B1 (en) * 2019-04-23 2020-10-27 국방과학연구소 The acceleration sensor applicable to a toward array sensor in underwater

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019118966A1 (en) * 2017-12-15 2019-06-20 Pgs Geophysical As Seismic pressure and acceleration sensor
EP4152054A1 (en) 2017-12-15 2023-03-22 PGS Geophysical AS Seismic pressure and acceleration sensor
US11871675B2 (en) 2017-12-15 2024-01-09 Pgs Geophysical As Seismic pressure and acceleration measurement
US11889760B2 (en) 2017-12-15 2024-01-30 Pgs Geophysical As Seismic pressure and acceleration sensor
KR102170736B1 (en) * 2019-04-23 2020-10-27 국방과학연구소 The acceleration sensor applicable to a toward array sensor in underwater

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