Non-contact type transducer having multi-loop coil for plate member

A transducer comprising:

• a multi-loop coil having two or more closed loop portions and disposed above and separate from a plate member;
• a magnet having a neutral plane between north (N) and south (S) poles parallel to a surface of the plate member and functioning as a static magnetic field former;
• and
• conductor foil attached on the plate member so as to cover a surface portion of the plate member facing the multi-loop coil,
• wherein an eddy current that flows on a surface of the conductor foil is generated by controlling a current that flows through the multi-loop coil, and Lorentz forces are applied in directions perpendicular to the surface of the plate member due to the eddy current and a magnetic field component parallel to the surface of the plate member of a static magnetic field formed by the static magnetic field former, and
• wherein an eddy current is generated on the conductor foil contacting regions of the plate member below a magnetic field component parallel to the surface of the plate member of a static magnetic field formed by the static magnetic field former when vibration is transmitted on the plate member, and an electromotive force is generated on the multi-loop coil so that a magnetic field component is formed in a direction opposite to a direction of a magnetic field component formed due to the eddy current in order to offset the magnetic field component formed due to the eddy current, and the vibration transmitted on the plate member is measured from the electromotive force.

A transducer comprising:

• a multi-loop coil having two or more closed loop portions and disposed above and separate from a plate member;
• and
• a power source for applying a variable current signal to the multi-loop coil,
• wherein the plate member is formed of a conductor, and
• wherein an eddy current that flows on a surface of the plate member is generated by controlling a current that flows through the multi-loop coil, and Lorentz forces are applied in directions perpendicular to the surface of the plate member due to the eddy current and a magnetic field component parallel to the surface of the plate member of a static magnetic field formed by the static magnetic field former.

A transducer comprising:

• a multi-loop coil having two or more closed loop portions and disposed above and separate from a plate member;
• a power source for applying a variable current signal to the multi-loop coil;
• and
• conductor foil attached on the plate member so as to cover a surface portion of the plate member facing the multi-loop coil,
• wherein an eddy current that flows on a surface of the conductor foil is generated by controlling a current that flows through the multi-loop coil, and Lorentz forces are applied in directions perpendicular to the surface of the plate member due to the eddy current and a magnetic field component parallel to the surface of the plate member of a static magnetic field formed by the static magnetic field former.