Physical quantity sensor and inertial measurement unit
According to a physical quantity sensor, a first movable electrode group, a second movable electrode group, a third movable electrode group, and a fourth movable electrode group are arranged in this order along a first direction. In a third direction, a thickness of a second movable electrode in the second movable electrode group and a thickness of a third movable electrode in the third movable electrode group are different from a thickness of a first movable electrode in the first movable electrode group and a thickness of a fourth movable electrode in the fourth movable electrode group. When an imaginary line extending in a second direction from a center of a fixed portion is an axis of symmetry, the first movable electrode is disposed line-symmetrically with the fourth movable electrode, and the second movable electrode is disposed line-symmetrically with the third movable electrode.
1 . A physical quantity sensor comprising:
when directions orthogonal to one another are a first direction, a second direction, and a third direction,
a fixed portion fixed to a base body, the fixed portion extending along the first direction;
a support beam having one end coupled to the fixed portion and extending along the first direction;
a fixed electrode portion provided at the base body; and
a movable body, wherein
the fixed electrode portion includes
a first pedestal provided at the base body,
a first fixed electrode group including a plurality of first fixed electrodes that extend from the first pedestal along the second direction,
a second pedestal provided at the base body,
a second fixed electrode group including a plurality of second fixed electrodes that extend from the second pedestal along the second direction,
a third pedestal provided at the base body,
a third fixed electrode group including a plurality of third fixed electrodes that extend from the third pedestal along the second direction,
a fourth pedestal provided at the base body, and
a fourth fixed electrode group including a plurality of fourth fixed electrodes that extend from the fourth pedestal along the second direction,
the movable body includes a movable electrode portion,
the movable electrode portion includes
a first movable electrode group including a plurality of first movable electrodes respectively facing the plurality of first fixed in the first direction,
a second movable electrode group including a plurality of second movable electrodes respectively facing the plurality of second fixed electrodes in the first direction,
a third movable electrode group including a plurality of third movable electrodes respectively facing the plurality of third fixed electrodes in the first direction, and
a fourth movable electrode group including a plurality of fourth movable electrodes respectively facing the plurality of fourth fixed electrodes in the first direction,
the first movable electrode group, the second movable electrode group, the third movable electrode group, and the fourth movable electrode group are arranged in this order along the first direction,
a thickness along the third direction of each of the plurality of second movable electrodes is different from a thickness along the third direction of each of the plurality of first movable electrodes,
a thickness along the third direction of each of the plurality of third movable electrodes is different from a thickness along the third direction of each of the plurality of fourth movable electrodes,
when an imaginary line extending in the second direction from a center of the fixed portion is an axis of symmetry, the first movable electrode group is disposed line-symmetrically with the fourth movable electrode group, and the second movable electrode group is disposed line-symmetrically with the third movable electrode group,
the fixed portion aligns with the second and third pedestals along the second direction,
a damper is configured to damp a rotational vibration of the movable body about the third direction as a rotation axis,
the damper is configured with fixed comb teeth and movable comb teeth that face each other along the first direction,
the movable comb teeth are connected to the movable body, and the fixed comb teeth are fixed to the base body, and
the fixed comb teeth extend along the second direction, and the movable comb teeth extend along the second direction.
2 . The physical quantity sensor according to claim 1 , wherein
the support beam includes
a first support beam having one end fixed to the fixed portion and extending in the first direction, and
a second support beam having one end fixed to the fixed portion and extending in an opposite direction of the first direction,
the movable body includes
a first coupling portion having one end side coupled to the other end of the first support beam and extending in the second direction,
a second coupling portion having one end side coupled to the other end of the second support beam and extending in the second direction, and
a base coupling the first coupling portion to the second coupling portion and extending in the first direction, and
the first movable electrode group, the second movable electrode group, the third movable electrode group, and the fourth movable electrode group are coupled to the base of the movable body.
3 . The physical quantity sensor according to claim 1 , wherein
the fixed portion includes
a first fixed portion, and
a second fixed portion disposed away from the first fixed portion in an opposite direction of the first direction,
the support beam includes
a first support beam having one end fixed to the first fixed portion and extending in the opposite direction of the first direction, and
a second support beam having one end fixed to the second fixed portion and extending in the first direction,
the movable body includes
a coupling portion having one end side coupled to the other end of the first support beam and the other end of the second support beam and extending in the second direction,
a first base coupled to the other end side of the coupling portion and extending in the first direction, and
a second base coupled to the other end side of the coupling portion and extending in the opposite direction of the first direction,
the first movable electrode group and the second movable electrode group are coupled to the second base, and
the third movable electrode group and the fourth movable electrode group are coupled to the first base.
4 . The physical quantity sensor according to claim 1 , wherein
the support beam includes
a first support beam having one end fixed to the fixed portion and extending in the first direction, and
a second support beam having one end fixed to the fixed portion and extending in an opposite direction of the first direction,
the movable body includes
a first coupling portion having one end side coupled to the other end of the first support beam and extending in the second direction,
a second coupling portion having one end side coupled to the other end of the second support beam and extending in the second direction,
a first base extending from the first coupling portion in the opposite direction of the first direction, and
a second base extending from the second coupling portion in the first direction,
the first movable electrode group and the second movable electrode group are coupled to the second base, and
the third movable electrode group and the fourth movable electrode group are coupled to the first base.
5 . The physical quantity sensor according to claim 1 , wherein
the fixed portion includes
a first fixed portion, and
a second fixed portion disposed away from the first fixed portion in an opposite direction of the first direction,
the support beam includes
a first support beam having one end fixed to the first fixed portion and extending in the opposite direction of the first direction, and
a second support beam having one end fixed to the second fixed portion and extending in the first direction,
the movable body includes
a coupling portion having one end side coupled to the other end of the first support beam and the other end of the second support beam and extending in the second direction,
a first base coupled to the coupling portion and extending in the first direction, and
a second base coupled to the coupling portion and extending in the opposite direction of the first direction,
the first movable electrode group and the second movable electrode group are coupled to the second base, and
the third movable electrode group and the fourth movable electrode group are coupled to the first base.
6 . An inertial measurement unit comprising:
the physical quantity sensor according to claim 1 ; and
a controller configured to perform control based on a detection signal output from the physical quantity sensor.