MEMS ELECTROSTATIC ACTUATOR

• US 20140076697A1
• Filed: 09/13/2012
• Published: 03/20/2014
• Est. Priority Date: 09/13/2011
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Gupta, Arun K., McDonald, William C.
• Granted Patent: US 9,040,854 B2
• Time in Patent Office: Days
• US Class Current: 200/181
• CPC Class Codes: B81B 2201/016 having a bridge fixed on two ends and connected to one or more dimples
• CPC Class Codes: B81B 2201/0221 Variable capacitors
• CPC Class Codes: B81B 2203/0109 Bridges
• CPC Class Codes: B81B 2203/0181 See-saws
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 2203/058 Rotation out of a plane parallel to the substrate
• CPC Class Codes: B81B 2203/06 Devices comprising elements which are movable in relation to each other, e.g. slidable or rotatable
• CPC Class Codes: B81B 3/0008 Structures for avoiding electrostatic attraction, e.g. avoiding charge accumulation
• CPC Class Codes: B81B 3/001 Structures having a reduced contact area, e.g. with bumps or with a textured surface
• CPC Class Codes: B81B 3/0013 Structures dimensioned for mechanical prevention of stiction, e.g. spring with increased stiffness
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: H02N 2/12 Constructional details

Abstract

A MEMS electrostatic actuator includes a bottom plate affixed to a substrate and a top plate suspended above the bottom plate. The top plate has a parallel plate center section and two rotating members electrically connected to the center section. Each rotating member is attached centrally of the rotating member for rotation about an axis of rotation to a set of anchor posts. The attachment includes at least one pair of torsional springs attached along each axis, each spring comprising a rectangular metal square that twists as the rotational members rotate. Electrostatic pull-down electrodes are underneath each rotational member.

Claims

1. A MEMS electrostatic actuator, comprising:

a bottom plate affixed to a substrate;

a top plate suspended above the bottom plate;

the top plate comprising a parallel plate center section and two rotating members electrically connected to the center section;

each rotating member is attached centrally of the rotating member for rotation about an axis of rotation to a set of anchor posts;

the attachment including at least one pair of torsional springs attached along each axis, each spring comprising a rectangular metal square that twists as the rotational members rotate; and

electrostatic pull-down electrodes underneath each rotational member.