Acceleration sensor and electronic device

• US 8,573,058 B2
• Filed: 02/23/2010
• Issued: 11/05/2013
• Est. Priority Date: 02/24/2009
• Status: Active Grant

• Current Assignee: 138 East LCD Advancements Limited (Vector Capital Corporation)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Oshio, Masahiro
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US12/710,569
• Publication Number:
  US 20100212426A1
• Time in Patent Office: 1,351 Days
• Field of Search: 735/143.2, 735/143.6, 735/143.8, 735/141.6
• US Class Current: 73/514.32
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type

Abstract

An acceleration sensor includes: a support member; a fixed electrode provided on the support member; a movable unit; a movable electrode provided on the movable unit and disposed opposed to the fixed electrode to generate capacity; and a projection extending from the opposed surface of at least either the fixed electrode or the movable electrode in one direction within the surface.

Claims

1. An acceleration sensor comprising:

a support member;

a fixed electrode extending from a first base of the support member in a first direction, the fixed electrode being in the form of an arm;

a movable unit;

a movable electrode extending from a second base of the movable unit in a second direction opposite to the first direction and disposed opposite to the fixed electrode across a gap, the movable electrode being in the form of an arm;

an elastically deformable connection member connecting the support member and the movable unit;

the fixed electrode has an opposite surface opposite to the movable electrode; and

a projection formed at the opposite surface of the fixed electrode, wherein

a first tip of the fixed electrode is adjacent to the movable unit,

the projection is continuously formed from the first base to the first tip in the first direction,

the projection is projected from the opposite surface toward the movable electrode, and

a first width of the fixed electrode where the projection is formed, in a width direction perpendicular to the first direction is larger than a second width of the fixed electrode, where the projection is not formed, in the width direction.

2. The acceleration sensor according to claim 1, wherein the opposite surface has one end in a third direction perpendicular to the first and second directions and another end opposite the one end, the projection is formed at least at either the one end or the other end.

3. The acceleration sensor according to claim 1, wherein

the movable electrode has another a opposite surface opposite to the fixed electrode,

another projection is formed at the another opposite surface,

a second tip of the movable electrode is adjacent to the support member,

the another projection is continuous formed from he second base to the second tip in the second direction,

the another projection is projected from the another opposite surface toward the opposite surface, and

a third width of the movable electrode, where the another projection is formed, in the width direction perpendicular to the second direction is larger than a fourth width of the movable electrode, where the another projection is not formed, in the width direction.

4. The acceleration sensor according to claim 1, wherein each of the fixed electrode, the movable electrode, the support member, and the movable unit has a laminated layer structure alternately piled up a conductive layer and an insulated layer.

5. The acceleration sensor according to claim 4, wherein the projection is formed by the use of the conductive layer or the insulated layer.

6. The acceleration sensor according to claim 1, wherein each of the fixed electrode, the movable electrode, the support member, and the movable unit is formed by the use of monocrystal silicon.

7. An electronic device comprising the acceleration sensor according to claim 1.

8. An electronic device comprising the acceleration sensor to claim 2.

9. An electronic device comprising the acceleration sensor according to claim 3.

10. An electronic device comprising the acceleration sensor to claim 4.

11. An electronic device comprising the acceleration sensor to claim 5.

12. An electronic device comprising the acceleration sensor to claim 6.

13. An acceleration sensor comprising:

a support member;

a fixed electrode extending from a first base of the support member in a first direction, the fixed electrode being in the form of an arm;

a movable unit;

a movable electrode extending from a second base of the movable unit in a second direction opposite to the first direction and disposed opposite to the fixed electrode across a gap, the movable electrode being in the form of an arm;

an elastically deformable connection member connecting the support member and the movable unit;

the movable electrode has an opposite surface opposite to the fixed electrode; and

a projection formed at the opposite surface of the movable electrode, wherein

a first tip of the movable electrode is adjacent to the support member,

the projection is continuously formed from the second base to the first tip in the second direction,

the projection is projected from the opposite surface toward the fixed electrode, and

a first width of the movable electrode, where the projection is formed, in a width direction perpendicular to the second direction is larger than a second width of the movable electrode, where the projection is not formed, in the width direction.

14. The acceleration sensor according to claim 13, wherein

the opposite surface has one end in a third direction perpendicular to the first and second directions and another end opposite the one end, the projection is formed at least at either the one end or the other end.

15. The acceleration sensor according to claim 13, wherein

the fixed electrode has another opposite surface opposite to the movable electrode,

another projection is formed at the another opposite surface,

a second tip of the fixed electrode is adjacent to the movable unit,

the another projection is continuously formed from the first base to the second tip in the first direction,

the another projection is projected from the another opposite surface toward the opposite surface, and

a third width of the fixed electrode, where the another projection is formed, in the width direction perpendicular to the first direction is larger than a fourth width of the fixed electrode, where the another projection is not formed, in the width direction.

16. The acceleration sensor according to claim 13, wherein

each of the fixed electrode, the movable electrode, the support member, and the movable unit has a laminated layer structure of a conductive layer and an insulated layer.

17. The acceleration sensor according to claim 16, wherein

the projection is formed by the conductive layer or the insulated layer.

18. The acceleration sensor according to claim 13, wherein

each of the fixed electrode, the movable electrode, the support member, and the movable unit is formed of monocrystal silicon.