Physical quantity sensor and electronic apparatus

• US 9,073,744 B2
• Filed: 04/05/2013
• Issued: 07/07/2015
• Est. Priority Date: 04/09/2012
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Tanaka, Satoru
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): Hopkins, Brandi N
• Application Number:
  US13/857,317
• Publication Number:
  US 20130264661A1
• Time in Patent Office: 823 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B81B 3/0018 Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00

Abstract

A physical quantity sensor includes a substrate, a movable body which has first and second sections and in which a first movable electrode section is provided in the first section, a beam section which supports the movable body so as to be able to be displaced, and a first fixed electrode section disposed on the substrate. The first fixed electrode section is provided at a position overlapping an end of the first section in the second axis direction in plan view, and is provided in a range of 0.0500X≦L≦0.816X assuming that the width of the first section in the second axis direction is X and the width of a portion of the first fixed electrode section in the second axis direction overlapping the movable body in plan view is L.

Claims

1. A physical quantity sensor comprising:

a movable body that has a first axis as a rotation axis in a first direction, that has first and second edges extending in the first direction and that is divided into first and second areas with respect to the first axis as a boundary in a plan view, a first movable electrode being provided in the first area along the first edge;

a beam that is located on the first axis and that supports the movable body; and

a first fixed electrode that is provided on a substrate, that extends along the first edge, and that is spaced apart from the movable body so as to face the first movable electrode,

wherein the first fixed electrode is provided at a position overlapping with the first edge of the movable body in the plan view, and the first fixed electrode is provided in a range of 0.0500X≦

L≦

0.816X when a width of the first area in a second direction perpendicular to the first direction is X and a width of an overlapped area between the first fixed electrode and the movable body in the second direction in the plan view is L, and

the first fixed electrode extends outwardly from the first edge of the movable body in the second direction in the plan view.

2. The physical quantity sensor according to claim 1,

wherein the first fixed electrode is provided in a range of 0.164X≦

L≦

0.633X.

3. The physical quantity sensor according to claim 1,

wherein, in the movable body, the width of the first area in the second direction is smaller than a width of the second area in the second direction.

4. The physical quantity sensor according to claim 1,

wherein a second movable electrode is provided in the second area and extends in the second direction, and

a second fixed electrode is provided on the substrate, extends in the second direction, and is spaced apart from the movable body so as to face the second movable electrode.

5. The physical quantity sensor according to claim 4,

wherein a region where the first movable electrode and the first fixed electrode overlap each other and a region where the second movable electrode and the second fixed electrode overlap each other are symmetrical with respect to the first axis in the plan view.

6. The physical quantity sensor according to claim 1,

wherein the first fixed electrode extends from the first area in the first direction in the plan view.

7. The physical quantity sensor according to claim 1,

wherein a first mass of the first area is smaller than a second mass of the second area.

8. The physical quantity sensor according to claim 1,

wherein the substrate is formed of an insulating material, and the movable body is formed of a semiconductor material.

9. An electronic apparatus comprising:

a display;

the physical quantity sensor according to claim 1; and

a case that houses the display and the physical quantity sensor.