PHYSICAL QUANTITY SENSOR AND ELECTRONIC DEVICE

• US 20120210789A1
• Filed: 02/16/2012
• Published: 08/23/2012
• Est. Priority Date: 02/18/2011
• Status: Active Grant

• Current Assignee: 138 East LCD Advancements Limited (Vector Capital Corporation)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: KANEMOTO, Kei
• Granted Patent: US 9,273,962 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 19/5733 Structural details or topology
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames

Abstract

A physical quantity sensor includes: a substrate; first and second displacement members in a spatial plane on the substrate and having rotation shafts; fixed electrodes on the substrate opposed to the first and second displacement members; a support member supporting the rotation shafts; fixing members supporting the support member via a spring unit; and a driving unit oscillating the support member in an oscillation direction. Each of the first and second displacement members shifts perpendicularly to the spatial plane around an axis of the corresponding rotation shaft. Each rotation shaft is shifted in an opposite direction from the center of gravity of the corresponding displacement member.

Claims

1. A physical quantity sensor comprising:

a substrate;

a first displacement member and a second displacement member each of which is disposed in a spatial plane on the substrate and has a rotation shaft;

fixed electrodes disposed on the substrate at positions opposed to the first displacement member and the second displacement member;

a support member which supports the respective rotation shafts of the first displacement member and the second displacement member;

a fixing member which supports the support member via a spring unit; and

a driving unit which oscillates the support member in an oscillation direction,

wherein

each of the first displacement member and the second displacement member shifts in a direction perpendicular to the spatial plane around an axis of the corresponding rotation shaft,

each of the rotation shafts of the first displacement member and the second displacement member is disposed at a position shifted from the center of gravity of the corresponding displacement member, and

the shift direction of the rotation shaft of the first displacement member from the center of gravity of the first displacement member is opposite to the shift direction of the rotation shaft of the second displacement member from the center of gravity of the second displacement member.

2. The physical quantity sensor according to claim 1, wherein each of the rotation shafts is disposed in parallel with the oscillation direction of the support member.

3. The physical quantity sensor according to claim 1, wherein the first and second displacement members are symmetrically disposed.

7. The physical quantity sensor according to claim 1, wherein a detection target of the physical quantity sensor is an angular velocity generated around an axis extending in the direction perpendicular to the oscillation direction in the plan view.

8. An electronic device, comprising the physical quantity sensor according to claim 1.

4. A physical quantity sensor comprising:

a substrate; and

a first oscillator and a second oscillator each of which is disposed in a spatial plane on the substrate,

wherein

the first oscillator includes a first displacement member and a second displacement member each of which has a rotation shaft, and a first support member which supports the respective rotation shafts of the first displacement member and the second displacement member,

the second oscillator includes a third displacement member and a fourth displacement member each of which has a rotation shaft, and a second support member which supports the respective rotation shafts of the third displacement member and the fourth displacement member,

the physical quantity sensor further includes fixed electrodes disposed on the substrate at positions opposed to the first through fourth displacement members, a fixing member which supports the first support member and the second support member via a spring unit, and a driving unit which oscillates the first support member and the second support member,

the first oscillator and the second oscillator oscillate in directions opposite to each other,

each of the first through fourth displacement members shifts in a direction perpendicular to the spatial plane around an axis of the corresponding rotation shaft,

each of the rotation shafts of the first through fourth displacement members is disposed at a position shifted from the center of gravity of the corresponding displacement member,

the shift direction of the rotation shaft of the first displacement member from the center of gravity of the first displacement member is opposite to the shift direction of the rotation shaft of the second displacement member from the center of gravity of the second displacement member, and

the shift direction of the rotation shaft of the third displacement member from the center of gravity of the third displacement member is opposite to the shift direction of the rotation shaft of the fourth displacement member from the center of gravity of the fourth displacement member.

5. The physical quantity sensor according to claim 4, wherein the first oscillator and the second oscillator are connected with each other via a junction spring.

6. The physical quantity sensor according to claim 4, wherein

when capacitances between the fixed electrodes and the first displacement member, the second displacement member, the third displacement member, and the fourth displacement member are C1, C2, C3, and C4, respectively, the output from the physical quantity sensor is expressed as (C1+C2)−

(C3+C4).