Title:
ELECTROMAGNETIC ACOUSTIC TRANSDUCER
Document Type and Number:
Japanese Patent JP3886843
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide an EMAT (electromagnetic acoustic transducer) capable of transmitting/receiving a surface SH (shear horizontal) wave of high frequency.
SOLUTION: As a magnet array 11 for generating a magnetostatic field, permanent magnets 13 are arranged so that their different polar surfaces face each other is used. Distances between the adjacent magnets 13 are set at an appropriate value, so that a magnetic field B in which magnetic field components perpendicular to the surface of an object 30 are inverted at a pitch somewhat similar to the width D of the magnet 13 can be formed in the vicinity of the object 30. A Lorentz force F is perpendicular to both the magnetic field B and an eddy current J(ω), and its direction is inverted by the above pitch by an interaction of the magnetic field B and the eddy current J(ω) induced in the vicinity of the surface of the object 30 caused by a high-frequency current I(ω) flowing through a spiral coil 17. The surface SH wave is generated in the vicinity of the surface of the object 30 by this Lorentz force. According to this configuration, since the pitch at which the magnetic field B is inverted can be made to be as half as that of a conventional PPM type EMAT, the high-frequency transmission/reception can be performed.
Inventors:
Ichi Yasui
Koichiro Kawashima
Ryuji Yamamoto
Koichiro Kawashima
Ryuji Yamamoto
Application Number:
JP2002126935A
Publication Date:
February 28, 2007
Filing Date:
April 26, 2002
Export Citation:
Assignee:
TOYOTA JIDOSHA KABUSHIKI KAISHA
Koichiro Kawashima
Ryuji Yamamoto
Koichiro Kawashima
Ryuji Yamamoto
International Classes:
G01N29/04; H04R13/00; G01N29/24; H04R1/20; (IPC1-7): H04R13/00; G01N29/04; G01N29/24; H04R1/20
Domestic Patent References:
| JP63208757A | ||||
| JP11125622A |
Attorney, Agent or Firm:
Kenji Yoshida
Toshihiko Kanayama
Jun Ishida
Toshihiko Kanayama
Jun Ishida