Piezoelectric vibration reed, piezoelectric vibrator, oscillator, electronic instrument, and radio timepiece

1. A piezoelectric vibration reed, comprising:

a pair of vibrating arm portions arranged in parallel to each other; and

a base portion integrally coupled to proximal ends of the pair of the vibrating arm portions in a longitudinal direction that the vibrating arm portions extend, wherein the base portion includes:

a connecting portion which is located on a distal end side of the base portion along the longitudinal direction and to which the proximal end of the vibrating arm portions are coupled; and

a mount portion located on a proximal end of the base portion along the longitudinal direction for mounting the base portion;

a narrow portion between the connecting portion and the mount portion, the narrow portion having a length narrower than a length of the connecting portion and a length of the mount portion in a width direction of the piezoelectric vibration reed which is perpendicular to the longitudinal direction;

a pair of notched portions notched respectively inwardly from both sides of the base portion in the width direction to form the narrow portion; and

ribs projecting outwardly in the width direction of the base portion and arranged in the interiors of the notched portions wherein the pair of notched portions accommodate the ribs such that outside end portions of the ribs in the width direction of the piezoelectric vibration reed are located inside the connecting portion and the mount portion;

wherein a combined length of the narrow portion and the ribs is narrower than the length of the connection portion and the length of the mount portion in the width direction of the piezoelectric vibration reed.

2. The piezoelectric vibration reed of claim 1 , wherein a route through which vibrations excited by the vibrating arm portions are transmitted to the base portion comprises the narrow portion formed between the notched portions.

3. The piezoelectric vibration reed of claim 1 , wherein the ribs are formed at intermediate portions of the narrow portion in a thickness direction orthogonal to the longitudinal direction and the width direction of the base portion.

4. The piezoelectric vibration reed of claim 1 , wherein the ribs are formed at one end of the narrow portion in a thickness direction orthogonal to the longitudinal direction and the width direction of the base portion.

5. The piezoelectric vibration reed of claim 1 , wherein the thickness of the ribs along a thickness direction is set to be ½ or smaller with respect to the thickness of the base portion in the thickness direction orthogonal to the width direction and the longitudinal direction of the base portion.

6. The piezoelectric vibration reed of claim 1 , wherein the thickness of the ribs along the thickness direction is set to be ⅓ or larger with respect to the thickness of the base portion in the thickness direction orthogonal to the width direction and the longitudinal direction of the base portion, thereby sufficiently securing rigidity of the base portion.

7. The piezoelectric vibration reed of claim 1 , wherein each notched portion has a circular shape.

8. The piezoelectric vibration reed of claim 1 , wherein a width of each notched portion in the longitudinal direction is gradually reduced from an outside toward an inside of the piezoelectric vibration reed in the width direction.

9. The piezoelectric vibration reed of claim 1 , wherein a width of each notched portion in the longitudinal direction is smaller than a width of the ribs in the longitudinal direction.

10. The piezoelectric vibration reed of claim 1 , wherein a distal end of a vibrating arm portion is enlarged to form a hammer-shape portion.

11. The piezoelectric vibration reed of claim 1 , wherein each vibrating arm portion comprises a groove having a rectangular shape extending in the longitudinal direction.

12. The piezoelectric vibration reed of claim 1 , wherein the connecting portion comprises a first base portion and a second base portion and a width of the connecting portion increases in a width direction orthogonal to the longitudinal direction, wherein a width of the first base portion is smaller than a width of the second base portion.

13. The piezoelectric vibration reed of claim 1 , wherein the mount portion further comprises side arms extended toward both sides.

14. A piezoelectric vibrator comprising the piezoelectric vibration reed of claim 1 , wherein the piezoelectric vibration reed of the invention is hermetically sealed in a package.

15. An oscillator comprising the piezoelectric vibrator of claim 14 , wherein the piezoelectric vibrator is electrically connected to an integrated circuit as an oscillating element.

16. An electronic instrument comprising the piezoelectric vibrator of claim 14 , wherein the piezoelectric vibrator is electrically connected to a clocking unit.

17. A radio timepiece comprising the piezoelectric vibrator of claim 14 , wherein the piezoelectric vibrator is electrically connected to a filter portion.