Electronic device having a piezoelectric vibrating reed with a discontinuous electrode film
A piezoelectric vibrating reed includes a piezoelectric plate having a pair of vibrating arms provided parallel to each other, a base portion to integrally fix the pair of vibrating arms at a base end side thereof, and groove portions formed on both principal surfaces of the pair of vibrating arms in a constant length from base end portions toward tip end portions of the vibrating arms, and an electrode film formed of a base metal layer and a finishing metal layer laminated on outer surfaces of the piezoelectric plate and configured to vibrate the pair of vibrating arms when a predetermined voltage is applied thereon. The finishing metal layer of the electrode film is removed either partially or entirely at least in regions from the base end portions to the tip end portions of the vibrating arms.
1. A piezoelectric vibrating reed, comprising:
a piezoelectric plate having a pair of vibrating arms extending parallel to each other, a base portion integrally fixing the pair of vibrating arms thereto at a base end side thereof, and groove portions on principal surfaces of the pair of vibrating arms, the groove portions having the same length from base end portions toward tip end portions of the vibrating arms; and
an electrode film comprising a base metal layer and a finishing metal layer, the electrode film laminated on outer surfaces of the piezoelectric plate and configured to vibrate the pair of vibrating arms when a predetermined voltage is applied thereon,
wherein the finishing metal layer of the electrode film is at least partially discontinuous such that the base metal layer is exposed in regions of the vibrating arms between the base end portions and the tip end portions.
2. The piezoelectric vibrating reed according to claim 1 , wherein:
the finishing metal layer of the electrode film is at least partially discontinuous from the base end portions to positions spaced by at least the length of the groove portions.
3. The piezoelectric vibrating reed according to claim 2 , wherein:
the finishing metal layer of the electrode film is discontinuous on the principal surfaces and in the groove portions of the piezoelectric plate.
4. The piezoelectric vibrating reed according to claim 1 , wherein:
the base metal layer comprises chromium; and
the finishing metal layer comprises gold.
5. A piezoelectric vibrator, comprising the piezoelectric vibrating reed set forth in claim 1 .
6. An oscillator, comprising:
the piezoelectric vibrator set forth in claim 5 ,
wherein the piezoelectric vibrator is electrically connected to an integrated circuit as a resonator.
7. An electronic device, comprising:
the piezoelectric vibrator set forth in claim 5 ,
wherein the piezoelectric vibrator is electrically connected to a clock portion.
8. A wave clock, comprising:
the piezoelectric vibrator set forth in claim 5 ,
wherein the piezoelectric vibrator is electrically connected to a filter portion.
9. A piezoelectric vibrating reed having a serial resonance resistance value that is substantially independent of relative structural dimensions, the vibrating reed comprising:
a piezoelectric plate having a pair of vibrating arms extending parallel to each other, a base portion integrally fixing the pair of vibrating arms thereto at a base end side thereof, and groove portions on principal surfaces of the pair of vibrating arms, the groove portions having the same length from base end portions toward tip end portions of the vibrating arms; and
an electrode film comprising a base metal layer and a finishing metal layer, the electrode film laminated on outer surfaces of the piezoelectric plate in an electrode pattern configured to vibrate the pair of vibrating arms when a predetermined voltage is applied thereon,
wherein the electrode film comprises a single layer of base metal in the groove portions and regions of the vibrating arms in immediate proximity to the groove portions.