Tuning fork flexural crystal vibration device, crystal vibrator, and crystal oscillator
View Patent ↗A tuning fork flexural crystal vibration device includes a base, two vibration arms, grooves, electrodes, and wirings. The base has a flat plate shape. The two vibration arms have flat panel shapes extending from a side surface of the base in the same direction. The grooves are provided for the two vibration arms so as to extend from base-side end portions of the vibration arms along the longitudinal direction of the vibration arms and are depressed in the thickness direction of the vibration arms. The grooves include front-side grooves which open in the front main surfaces of the vibration arms and are provided at least one by one for each vibration arm, and rear-side grooves which open in the rear main surfaces of the vibration arms and are provided at least one by one for each vibration arm. The bottom surface of the front-side groove does not face the bottom surface of the rear-side groove provided in the same vibration arm in which the front-side groove is provided. The electrodes are formed on the surfaces of the base and the two vibration arms. The wirings electrically connect the electrodes to each other. A crystal vibrator and crystal oscillator are also disclosed.
1. A tuning fork flexural crystal vibration device comprising:
a base having a flat plate shape;
two vibration arms having flat panel shapes extending from a side surface of said base in the same direction;
a plurality of grooves which are provided for said two vibration arms so as to extend from base-side end portions of said vibration arms along a longitudinal direction of said vibration arms and are depressed in a thickness direction of said vibration arms, said plurality of grooves including front-side grooves which open in front main surfaces of said vibration arms and are provided at least one by one for each vibration arm, and rear-side grooves which open in rear main surfaces of said vibration arms and are provided at least one by one for each vibration arm, and said front-side groove having a bottom surface not facing a bottom surface of said rear-side groove provided in said same vibration arm in which said front-side groove is provided;
a plurality of electrodes which are formed on surfaces of said base and said two vibration arms; and
wirings which electrically connect said plurality of electrodes to each other.
2. A device according to claim 1 , wherein
an angle defined by a bottom surface of each groove and a side wall surface of said groove on a base side, and an angle defined by the bottom surface of each groove and a side wall surface of said groove on a vibration arm distal end side are obtuse angles, and
a side wall surface of said front-side groove on the base side faces a side wall surface of said rear-side groove on the vibration arm distal end side which is provided in said same vibration arm in which said front-side groove is provided.
3. A device according to claim 1 , wherein
an angle defined by a bottom surface of each groove and a side wall surface of said groove on a base side, and an angle defined by the bottom surface of each groove and a side wall surface of said groove on a vibration arm distal end side are obtuse angles, and
a side wall surface of said front-side groove on the vibration arm distal end side faces a side wall surface of said rear-side groove on the base side which is provided in said same vibration arm in which said front-side groove is provided.
4. A device according to claim 1 , wherein depths of said plurality of grooves are 3/10 to 9/10 of thicknesses of said two vibration arms.
5. A device according to claim 1 , wherein said plurality of front-side grooves and said plurality of rear-side grooves are provided for each vibration arm, said plurality of front-side grooves provided for said same vibration arm are arranged parallel to a widthwise direction of said vibration arm, and said plurality of rear-side grooves provided for said same vibration arm are arranged parallel to the widthwise direction of said vibration arm.
6. A crystal vibrator comprising:
a packing container in which a recess portion having an opening in one main surface is formed;
a tuning fork flexural crystal vibration device which is mounted in the recess portion;
a plurality of external connection electrodes which are formed on an outer bottom surface of said packing container and are electrically connected to said tuning fork flexural crystal vibration device; and
a cover member which is placed on the opening of the recess portion to hermitically seal the recess portion,
said tuning fork flexural crystal vibration device comprising
a base having a flat plate shape,
two vibration arms having flat panel shapes extending from a side surface of said base in the same direction,
a plurality of grooves which are provided for said two vibration arms so as to extend from base-side end portions of said vibration arms along a longitudinal direction of said vibration arms and are depressed in a thickness direction of said vibration arms, said plurality of grooves including front-side grooves which open in front main surfaces of said vibration arms and are provided at least one by one for each vibration arm, and rear-side grooves which open in rear main surfaces of said vibration arms and are provided at least one by one for each vibration arm, and said front-side groove having a bottom surface not facing a bottom surface of said rear-side groove provided in said same vibration arm in which said front-side groove is provided,
a plurality of electrodes which are formed on surfaces of said base and said two vibration arms, and
wirings which electrically connect said plurality of electrodes to each other.
7. A crystal oscillator comprising:
a tuning fork flexural crystal vibration device; and
an oscillation circuit which is electrically connected to said tuning fork flexural crystal vibration device and is integrated with said tuning fork flexural crystal vibration device,
said tuning fork flexural crystal vibration device comprising
a base having a flat plate shape,
two vibration arms having flat panel shapes extending from a side surface of said base in the same direction,
a plurality of grooves which are provided for said two vibration arms so as to extend from base-side end portions of said vibration arms along a longitudinal direction of said vibration arms and are depressed in a thickness direction of said vibration arms, said plurality of grooves including front-side grooves which open in front main surfaces of said vibration arms and are provided at least one by one for each vibration arm, and rear-side grooves which open in rear main surfaces of said vibration arms and are provided at least one by one for each vibration arm, and said front-side groove having a bottom surface not facing a bottom surface of said rear-side groove provided in said same vibration arm in which said front-side groove is provided,
a plurality of electrodes which are formed on surfaces of said base and said two vibration arms, and
wirings which electrically connect said plurality of electrodes to each other.
8. An oscillator according to claim 7 , further comprising:
a packing container in which a recess portion having an opening in one main surface is formed, with said tuning fork flexural crystal vibration device and said oscillation circuit being mounted in the recess portion;
a plurality of external connection electrodes which are formed on an outer bottom surface of said packing container and are electrically connected to said tuning fork flexural crystal vibration device; and
a cover member which is placed on the opening of the recess portion to hermetically seal the recess portion.