US 5,331,854 A · Micromachined rate and acceleration sensor having vibrating beams

Abstract

Apparatus is disclosed for measuring the specific force and angular rotation rate of a moving body. A silicon substrate has first and second substantially planar and substantially parallel surfaces. An accelerometer is formed of the substrate and has a force sensing axis. An output signal is provided which is indicative of the moving body along the force sensing axis. The accelerometer is mounted so as to be movable along a vibration axis perpendicular to the force sensing axis. The accelerometer is driven so as to impart a dithering motion thereto of a predetermined frequency along the vibration axis. The accelerometer includes a frame, a proof mass and a hinge interconnected between the frame and the proof mass for rotating the proof mass about a hinge axis when the moving body is subjected to a force along the force sensing axis. The accelerometer further includes at least one vibrating beam having first and second ends respectively coupled to the frame and the proof mass, a longitudinal axis disposed perpendicular to the force sensing axis and the vibration axis, and a conductive path disposed along the vibrating beam. The hinge axis is substantially parallel to the vibration axis. A signal generator applies a periodic drive signal to the conductive path. The periodic drive signal has a resonant frequency that is a function of the force applied along the force sensing axis to the moving body.

Claims17

Dependent claims

Apparatus for measuring the specific force and angular rotation rate of a moving body, comprising:

a) a silicon substrate having first and second substantially planar surface disposed substantially parallel to each other;
b) an accelerometer formed of said substrate and having a force sensing axis for producing an output signal indicative of the acceleration of the moving body along said force sensing axis;
c) mounting means formed of said substrate for mounting said accelerometer such that said accelerometer can be moved along a vibration axis perpendicular to said force sensing axis;
d) drive means coupled to said accelerometer for imparting a dithering motion thereto of a predetermined frequency along said vibration axis;
e) said accelerometer comprising an accelerometer frame, a proof mass, hinge means interconnected between said frame and said proof mass for rotating said proof mass about a hinge axis when the moving body is subjected to a force along said force sensing axis, at least one vibrating beam having first and second ends respectively coupled to said frame and said proof mass and a longitudinal axis disposed perpendicular to said force sensing axis and said vibration axis, and a conductive path disposed along said vibrating beam, said hinge axis disposed substantially parallel to said vibration axis;
and
f) signal generator means for producing and applying to said conductive path a periodic drive signal having a resonant frequency that is a function of the force applied along said force sensing axis to the moving body.

4 more elements

An accelerometer for measuring specific force of acceleration of a moving body, comprising:

a) a monolithic substrate having first and second substantially planar surface disposed substantially parallel to each other;
b) an accelerometer formed of said substrate and having a force sensing axis for producing an output signal indicative of the acceleration of the moving body along said force sensing axis;
c) said accelerometer comprising an accelerometer frame, a proof mass, hinge means interconnected between said frame and said proof mass for allowing said proof mass about a hinge axis when the moving body is subjected to a force long said force sensing axis, said proof mass having a first end interconnected by said hinge means to said frame and a free end permitted to rotate freely about said hinge axis with respect to said frame, said proof mass further having a center of gravity and a pendulous axis aligned to intersect said center of gravity and said hinge axis, flexible means interconnected between said frame and said free end of proof mass for flexibly restraining the pivoting of said proof mass about said pendulous axis, at least one vibrating beam having first and second ends respectively coupled to said frame and said proof mass and a longitudinal axis, and conductive path disposed long said vibrating beam;
and
d) signal generator means for producing and applying to said conductive path a periodic drive signal having a resonant frequency that is a function of the force applied along said force sensing axis to the moving body.

2 more elements

Dependencies are inferred from the claim text.

Micromachined rate and acceleration sensor having vibrating beams

Life of this patent

Micromachined rate and acceleration sensor having vibrating beams

Life of this patent

Abstract

Claims17