Electro-mechanical transducer and manufacturing method of the same
AssigneeNational University Corporation Saitama University
InventorKensuke Kageyama
Life of this patent
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Abstract
A microphone-capsule includes a vibrator implemented by a conductor having a flat vibration surface, a dielectric-polarization plate that is defined by a flat first principal surface facing the vibration surface of the vibrating plate and a second principal surface facing parallel to the first principal surface and in which polarization directions are aligned, a back electrode joined to the second principal surface of the dielectric-polarization plate, and an induced-charge measuring unit configured to measure the charges induced between the vibrating plate and the back electrode, in association with the displacement of the vibration surface. The induced-charge measuring unit includes an amplifier connected to the back electrode and an output circuit connected to the amplifier.
Claims12
An electro-mechanical transducer comprising:
- a vibrator implemented by a conductor having a flat vibration surface;
- a first dielectric-polarization plate implemented by ferroelectric material, in which polarization directions are aligned in a same direction, the dielectric-polarization plate being defined by a flat first principal surface facing to the vibration surface and a second principal surface facing parallel to the first principal surface;
- a first back electrode joined to the second principal surface;
- and
- an induced-charge measuring unit configured to estimate equivalent charges induced on the first dielectric-polarization plate by displacement of the vibration surface, after measuring a potential between the first back electrode and the vibrator, by converting the measured potential into the equivalent charges.
A manufacturing method of an electro-mechanical transducer, comprising:
- on a dielectric-polarization plate implemented by a ferroelectric material, defined by a flat first principal surface and a second principal surface facing parallel to the first principal surface, joining a back electrode on the second principal surface of the dielectric-polarization plate;
- heating the dielectric-polarization plate to a charge-neutralization temperature between a depolarization temperature and the Curie temperature so as to remove charges induced on a surface of the dielectric-polarization plate;
- preparing a vibrator implemented by a conductor having a flat vibration surface, and accommodating the dielectric-polarization plate, the back electrode and the vibrator in a conductive case, at the charge-neutralization temperature so that the first principal surface faces to the vibrator, and then sealing a space between the vibrator and the dielectric-polarization plate;
- and
- after sealing the space between the vibrator and the dielectric-polarization plate, returning the dielectric-polarization plate to room temperature so as to align polarization directions in a same direction in the ferroelectric material.
Dependencies are inferred from the claim text.