# US 7,742,616 B2 · Electromagnetic acoustic transducer for generating and measuring bending vibration in rod member using anti-symmetric magnetic field structure

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- Number: US 7,742,616 B2
- Document ID: US7742616B2
- Status: Granted
- Kind: B2
- Application number: 11/287,370
- Filed: 2005-11-28
- Published: 2006-09-21
- Granted: 2010-06-22
- Earliest claimed: 2005-03-03
- Assignees: Seoul National University Industry Foundation
- Inventors: Yoon Young Kim; Soon Woo Han
- Web page: https://patentgrep.com/patent/US7742616B2

## CPC

- B06B 1/04: operating with electromagnetism (dynamo-electric motors with vibrating magnet, armature or coil system H02K33/00)
- G01N 27/90: using eddy currents
- G01N 29/2412: {using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; (investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18)}
- G01N 2203/005: Electromagnetic means
- G01N 2291/0421: Longitudinal waves
- G01N 2291/0422: Shear waves, transverse waves, horizontally polarised waves
- B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Provided is an electromagnetic acoustic transducer including a main body formed of a non-metal material and having a hollow portion, a magnetic field generation portion generating two magnetic fields parallel to a lengthwise direction of the rod member and in opposite directions to each other, at both sides of the rod member that is inserted in the hollow portion of the main body, and a coil wound around an outer circumferential surface of the main body.

## Claims

### Claim 1

An electromagnetic acoustic transducer which can generate and measure a bending vibration in a rod member comprising:
a main body formed of a non-metal material and having a hollow portion;
a magnetic field generation portion generating two magnetic fields parallel to a lengthwise direction of the rod member and in opposite directions to each other, at both sides of the rod member that is inserted in the hollow portion of the main body; and
a coil wound around an outer circumferential surface of the main body.

### Claim 2 (depends on 1)

The electromagnetic acoustic transducer as claimed in claim 1, wherein the magnetic field generation portion comprises:
a first pair of magnets arranged at one side of the main body and separated a predetermined distance from each other; and
a second pair of magnets arranged symmetrical to the first pair of magnets with respect to the rod member and generating a magnetic field in a direction opposite to a direction of a magnetic field generated by the first pair of magnets.

### Claim 3 (depends on 1)

The electromagnetic acoustic transducer as claimed in claim 1, wherein the main body comprises:
a coil portion around which the coil is wound; and
first and second rotational portions located at both sides of the coil portion, coupled to the coil portion, and capable of rotating at the same angle with respect to the coil portion.

### Claim 4 (depends on 3)

The electromagnetic acoustic transducer as claimed in claim 3, wherein the magnetic field generation portion is installed at each of the first and second rotational portions.