US-12625159-B2 - Physical quantity sensor and inertial measurement unit

US12625159B2US 12625159 B2US12625159 B2US 12625159B2US-12625159-B2

Abstract

A physical quantity sensor includes an anchor fixed to a substrate, a support beam, a fixed electrode unit, a movable body, and a damper unit. The fixed electrode unit is provided at the substrate. One end of the support beam is coupled to the anchor. The movable body includes a movable electrode unit and a frame unit. The movable electrode unit includes a movable electrode facing a fixed electrode of the fixed electrode unit. The frame unit couples the movable electrode unit and the other end of the support beam. The damper unit is coupled to the frame unit, is provided in a region surrounded by the support beam and the frame unit, and damps vibration of the frame unit in a first direction.

Inventors

Koichiro KOMIZO

Assignees

SEIKO EPSON CORPORATION

Dates

Publication Date: 20260512
Application Date: 20230220
Priority Date: 20220221

Claims (8)

1 . A physical quantity sensor for detecting, when directions orthogonal to one another are defined as a first direction, a second direction, and a third direction, a physical quantity in the third direction, the physical quantity sensor comprising: an anchor fixed to a substrate; a support beam having one end coupled to the anchor and extending in the first direction; a fixed electrode unit provided on the substrate; a frame unit connected to the other end of the support beam; a movable electrode unit connected to the frame unit; and a damper unit connected to the frame unit and configured to damp a rotational vibration of the frame unit about the third direction as a rotation axis, wherein the fixed electrode unit includes fixed electrode comb teeth extending in the first direction, the movable electrode unit includes movable electrode comb teeth extending in the first direction and facing the fixed electrode comb teeth, the frame unit includes: a first portion having one end connected to the other end of the support beam and extending in the second direction; and a second portion having one end connected to the other end of the first portion and extending in the first direction, the damper unit includes a damper anchor and a damper movable unit, wherein the damper movable unit limits a rotational motion of the frame unit about the third direction by colliding with the damper anchor, the damper anchor includes damper fixed comb teeth extending along the second direction and fixed to the substrate, the damper movable unit includes damper movable comb teeth extending along the second direction and facing the damper fixed comb teeth, a thickness along the third direction of each of the damper fixed comb teeth is the same as a thickness along the third direction of each of the damper movable comb teeth, the damper unit is disposed in an area of a side to which the support beam is connected to the first portion of the frame unit when viewed in a plan view from the third direction, the damper anchor is indirectly connected to an outer edge of the first portion of the frame unit on the side to which the support beam is connected, the damper unit is rectangular-shaped and has four sides in the plan view, and the four sides include first, second, and third sides, both ends of the first side are connected to the second and third sides, respectively, an entirety of the first side is directly adjacent to an inner side of the frame unit in the plan view, an entirety of the second side is directly adjacent to the fixed electrode unit in the plan view, and an entirety of the third side is directly adjacent to the support beam in the plan view.
2 . The physical quantity sensor according to claim 1 , wherein the frame unit further includes a reinforcer provided at an intersection where the first portion and the second portion intersect with each other.
3 . The physical quantity sensor according to claim 2 , wherein the reinforcer is configured to fix an intersection angle at which the first portion and the second portion intersect with each other.
4 . The physical quantity sensor according to claim 1 , wherein the support beam, the fixed electrode unit, and the movable electrode unit are arranged along the second direction in an order of the support beam, the fixed electrode unit, and the movable electrode unit, and the damper unit is provided between the fixed electrode unit and the support beam in the second direction.
5 . The physical quantity sensor according to claim 4 , wherein a frame reinforcer configured to reinforce the frame unit is provided between the fixed electrode unit and the support beam.
6 . The physical quantity sensor according to claim 5 , wherein the frame unit further includes a third portion having one end side coupled to another end side of the second portion and disposed along the second direction, and the frame reinforcer is coupled to the first portion and the third portion.
7 . 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.
8 . The physical quantity sensor according to claim 1 , wherein the damper anchor and the damper movable unit have the same thickness in the third direction.

Description

The present application is based on, and claims priority from JP Application Serial Number 2022-024692, filed Feb. 21, 2022, the disclosure of which is hereby incorporated by reference herein in its entirety. BACKGROUND 1. Technical Field The present disclosure relates to a physical quantity sensor and an inertial measurement unit. 2. Related Art JP-T-2021-524035 discloses a capacitive microelectromechanical acceleration sensor configured such that one or more rotor measurement plates and one or more stator measurement plates can measure movements of a proof mass in a direction of a sensing axis by capacitance measurement performed therebetween. In the acceleration sensor, one or more first rotor damping plates and one or more first stator damping plates form a first set of parallel plates orthogonal to a first damping axis, and the first damping axis is substantially orthogonal to the sensing axis. In the acceleration sensor disclosed in JP-T-2021-524035, the damping plates are provided outside the proof mass, there is a problem in that the size of an element increases. SUMMARY An aspect of the present disclosure relates to a physical quantity sensor for detecting, when directions orthogonal to one another are defined as a first direction, a second direction, and a third direction, a physical quantity in the third direction. The physical quantity sensor includes: an anchor fixed to a substrate; a support beam having one end coupled to the anchor; a fixed electrode unit provided at the substrate; a movable body including a movable electrode unit and a frame unit, the movable electrode unit including a movable electrode facing the fixed electrode of the fixed electrode unit, the frame unit coupling the movable electrode unit and another end of the support beam; and a damper unit coupled to the frame unit, provided in a region surrounded by the support beam and the frame unit, and configured to damp vibration of the frame unit in the first direction. Another aspect of the present disclosure relates to an inertial measurement unit including the physical quantity sensor described above and a controller configured to perform control based on a detection signal output from the physical quantity sensor. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a first configuration example of a physical quantity sensor according to an embodiment. FIG. 2 is a perspective view showing a three-dimensional shape of a detector. FIG. 3 is a perspective view showing a three-dimensional shape of a detector. FIG. 4 is an explanatory diagram of operations of the detectors. FIG. 5 is an explanatory diagram when a frame unit is deformed. FIG. 6 is a perspective view of a damper unit. FIG. 7 is a plan view of a comparative example of the physical quantity sensor according to the embodiment. FIG. 8 is a plan view of a modification of the first configuration example. FIG. 9 is a plan view of a modification of the first configuration example. FIG. 10 is a plan view of a second configuration example of the physical quantity sensor according to the embodiment. FIG. 11 is a plan view of a third configuration example of the physical quantity sensor according to the embodiment. FIG. 12 is a plan view of a modification of the third configuration example. FIG. 13 is an exploded perspective view showing a schematic configuration of an inertial measurement unit having the physical quantity sensor. FIG. 14 is a perspective view of a circuit board of the inertial measurement unit. DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the embodiment will be described. The embodiment to be described below does not unduly limit contents described in the claims. In addition, all of the configurations described in the embodiment are not necessarily essential constituent elements. 1. Physical Quantity Sensor A configuration example of a physical quantity sensor 1 according to the embodiment will be described with reference to FIG. 1 by taking an acceleration sensor that detects acceleration in a vertical direction as an example. FIG. 1 is a plan view of a first configuration example of the physical quantity sensor 1 according to the embodiment. Here, the plan view is a plan view in a direction orthogonal to a substrate 2. The physical quantity sensor 1 is a micro electro mechanical systems (MEMS) device, and is, for example, an inertial sensor. In FIG. 1 and FIGS. 2 to 12 to be described later, for convenience of description, dimensions of members, intervals between the members, and the like are schematically shown, and not all components are shown. For example, an electrode wiring, an electrode terminal, and the like are not shown. Further, in the following description, a case where a physical quantity detected by the physical quantity sensor 1 is the acceleration will be mainly described as an example, but the physical quantity is not limited to the acceleration and may be another physical quantity such as a velocity, pressure, displacement, an an