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US 4,365,181 AGranted
Piezoelectric vibrator with damping electrodes
AssigneeMurata Manufacturing Co., Ltd.
InventorTakashi Yamamoto
Life of this patent
Estimating the term…
Abstract
A piezoelectric vibrator includes an elongated piezoelectric plate deposited with electrodes for effecting mechanical vibration in the piezoelectric plate. A damper is deposited at each of opposite ends of the elongated piezoelectric plate so as to reduce the size of the piezoelectric plate.
Claims17
A piezoelectric vibrator of the energy trapping type which operates in the thickness vibrational mode, comprising:
- an elongated ceramic piezoelectric plate having first and second opposed planar surfaces, and having opposite pairs of lengthwise and widthwise edges;
- a first electrode deposited approximately at a center portion on said first planar surface of said piezoelectric plate;
- a second electrode deposited approximately at a center portion on said second planar surface of said piezoelectric plate in face-to-face relation with said first electrode, said first and second electrodes adapted to receive an electrical signal which will cause said piezoelectric plate to vibrate primarily in the thickness vibrational mode;
- first damping means comprising a third electrode located along the entirety of a first one of said widthwise edges and a damping material deposited entirely along said third electrode;
- second damping means comprising a fourth electrode located along the entirety of said second widthwise edges and a damping material deposited entirely along said fourth electrode;
- the distance G between that edge of said first electrode which is closest to one of said lengthwise edges of said piezoelectric plate and said one of said lengthwise edges of said piezoelectric plate, and the thickness T of the piezoelectric plate as measured between said planar surfaces satisfying the relationship 0.ltoreq.G/T.ltoreq.15;
- and
- said first and third electrodes being electrically connected to each other and said second and fourth electrodes being electrically connected to each other.
5 more elements
A piezoelectric vibrator of energy trapped type which operates in the thickness vibrational mode, comprising:
- an elongated ceramic piezoelectric plate having first and second half portions on respective sides of an imaginary center line drawn in the widthwise direction of said elongated piezoelectric plate at a position intermediate of the length of said piezoelectric plate, said plate having first and second opposed planar surfaces and opposite pairs of lengthwise and widthwise edges;
- a first electrode deposited approximately at a center portion of said first half portion and on said first planar surface of the piezoelectric plate;
- a second electrode deposited approximately at a center portion of said first half portion and on said second planar surface of said piezoelectric plate in face-to-face relation with said first electrode, said first and second electrodes adapted to receive an electrical signal which causes said elongated piezoelectric plate to vibrate primarily in the thickness mode;
- a third electrode deposited approximately at a center portion of said second half portion and on said first planar surface of said piezoelectric plate;
- a fourth electrode deposited approximately at a center portion of said second half portion and on said second planar surface of said piezoelectric plate in face-to-face relation with said third electrode, said third and fourth electrodes adapted to receive an electrical signal that causes said elongated piezoelectric plate to vibrate primarily in the thickness vibration mode;
- the minimum distance G between the edge of each of the first and third electrodes and the edge of said lengthwise edges of said elongated piezoelectric plate, and the thickness T as measured between said planar surfaces of said piezoelectric plate satisfies the following relation:
- 0.ltoreq.G/T.ltoreq.15;
- first damping means located at said first widthwise edge of said elongated piezoelectric plate along the entire edge thereof;
- second damping means located at said second widthwise edge of said elongated piezoelectric plate along the entire edge thereof;
- and
- third damping means applied at a center portion of said elongated piezoelectric plate along said center line.
8 more elements
Dependencies are inferred from the claim text.