External force measuring device

• US 20020078746A1
• Filed: 07/05/2001
• Published: 06/27/2002
• Est. Priority Date: 07/07/2000
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Mochida, Yoichi
• Granted Patent: US 6,539,803 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: G01P 15/125 by capacitive pick-up

Abstract

A center mass and a pair of outer masses are connected to each other via supporting beams displaceable in the X-axial direction. When an angular velocity sensor is operated, a vibration generator causes masses to vibrate substantially at opposite phases to each other with respect to the X-axial direction. In this state, if an angular velocity on the Y-axis is added, the displacements of the masses, caused when the masses are displaced in the Z-axial direction, are detected as the angular velocity. Moreover, fixing portions, formed on a substrate, support the nodes of the supporting beams corresponding to the nodes to suppress vibration of the masses from being transmitted to the substrate.

Claims

1. An external force measuring device comprising:

a substrate;

plural masses opposed to and spaced from the substrate, arranged in the Y-axial direction of three orthogonal axial directions, X-, Y-, and Z-axial directions, such as to be vibratable in the X-axial direction at opposite phases to each other;

a vibration generator for vibrating the plural masses;

supporting beams connecting the respective masses displaceably in the X-axial direction;

fixing portions provided between the supporting beams and the substrate; and

an external force detector for detecting, a displacement of the respective masses in one of the Y- and Z-axial directions, caused when an angular velocity or an acceleration acts on the respective masses.

2. An external force measuring device according to claim 1, wherein the fixing portions connect to the substrate the sites of the supporting beams corresponding to the nodes thereof caused when the respective masses are vibrated at opposite phases.

3. An external force measuring device according to one of claims 1 and 2, wherein the supporting beams support the respective masses displaceably in the Z-axial direction, and the external force detector detects the displacements of the respective masses, caused when the masses are displaced in the Z-axial direction.

4. An external force measuring device according to one of claims 1 and 2, wherein said respective masses comprise a first mass, and second masses positioned respectively on both of the sides in the Y-axial direction of the first mass, the first mass being supported by the supporting beams via mass-supporting beams displaceable in the Y-axial direction, and the external force detector detecting the displacement of the first mass caused when the first mass is displaced in the Y-axial direction.

5. An external force measuring device according to any one of claims 1 and 2, wherein said external force detector comprises:

a fixed detection electrode positioned on the substrate opposite the first mass and a movable detection electrode provided on the first mass and opposed to and spaced from the substrate in the Z-axial direction.

11. An external force measuring device according to one of claims 1, 2, 6 and 7, wherein the external force detector combines displacements of the respective masses caused when the masses are vibrated in opposite phases such as to be displaced in the Y-axial direction to detect at least angular velocity applied to the respective masses, separately from the acceleration.

14. An external force measuring device according to one of claims 1, 2, 6 and 7, wherein the external force detector comprises fixed detection electrodes each having plural electrodes fixedly formed in an interdigitated pattern on the substrate;

and movable detection electrodes formed on the masses and having plural electrode plates interdigitatedly engaged with and spaced from the plural electrodes of the respective fixed detection electrodes, defining spaces in the Y-axial direction; and

the external force detector detects variations in electrostatic capacitance between the fixed detection electrodes and the movable detection electrodes as the displacements of the masses.

6. An external force measuring device comprising:

a substrate;

a first mass opposed to and spaced from the substrate, arranged in the Y-axial direction of three orthogonal axial directions, X-, Y-, and Z-axial directions, such as to be vibratable in the X-axial direction;

a vibration generator for vibrating the plural masses;

second masses provided on both of the sides in the Y-axial direction of the first mass so as to sandwich the first mass and to be vibrated in the X-axial direction by the vibration generator;

third masses positioned between the first mass and the second masses so as to surround the first mass;

supporting beams connecting the second masses to each other displaceably in the X-axial direction;

connecting portions connecting the third masses to the supporting beams;

mass-supporting beams connecting the first mass to the third masses displaceably in the Y-axial direction;

fixing portions provided between the substrate and the supporting beams and connecting the supporting beams to the substrate; and

an external force detector for detecting a displacement in the Y-axial direction of the first mass caused when an angular velocity acts on the first mass, said first and third masses, and said second and fourth masses being vibrated at opposite phases to each other.

7. An external force measuring device according to claim 6, wherein said fixing portions connect to the substrate the sites of the supporting beams corresponding to the nodes thereof caused when the first and third masses and the second mass are vibrated at opposite phases to each other.

8. An external force measuring device according to one of claims 6 and 7, and the second masses are positioned on both of the sides in the Y-axial direction of the first mass, and the first and second masses are connected to the supporting beams via the first and second mass supporting beams displaceable in the Y-axial direction, respectively.

12. An external force measuring device according to claim 8, wherein said external force detector comprises:

fixed detection electrodes positioned between the first mass and the second masses and provided on the substrate;

first movable detection electrodes provided on the first mass and opposed to and spaced in the Y-axial direction from the fixed detection electrodes; and

second movable detection electrodes provided on the second masses and opposed to and spaced in the Y-axial direction from the fixed detection electrodes, the external force detecting means detector, in parallel, displacements of the first and second movable detection electrodes with respect to the fixed detection electrodes as variations in electrostatic capacitance.

9. An external force measuring device comprising:

a substrate;

a first mass opposed to and spaced from the substrate such as to be vibratable along the X-axial direction of three orthogonal axial directions is, X-, Y-, and Z-axial directions;

second masses provided on both of the sides in the Y-axial direction of the first mass so as to sandwich the first mass such as vibratable in the X-axial direction;

third masses positioned between the first mass and the second masses so as to surround the first mass;

fourth masses surrounding the second masses;

a vibration generator for vibrating the first mass, the second, third, and fourth masses;

supporting beams connecting the fourth masses to each other displaceably in the X-axial direction;

connecting portions connecting the third masses to the supporting beams;

first mass supporting beams connecting the first mass to the third masses displaceably in the Y-axial direction;

second mass supporting beams connecting the second masses to the fourth masses displaceably in the Y-axial direction;

fixing portions provided between the substrate and the supporting beams and connecting the supporting beams to the substrate; and

an external force detector for detecting, the displacement in the Y-axial direction of the first and second masses, caused when an angular velocity or acceleration acts on the first and second masses, said first and third masses, and said second and fourth masses being vibrated at opposite phases to each other.

10. An external force measuring device according to claim 9, wherein the fixing portions connect to the substrate the sites of the supporting beams corresponding to the nodes caused when the first and third masses and the second and fourth masses are vibrated at opposite phases to each other.

13. An external force measuring device according to any one of claims 6, 7, 9 and 10, wherein said external force detector comprises:

a first displacement detecting portion for detecting a displacement caused when the first mass, which is one of the first and second masses vibrating at opposite phases to each other, is displaced in the Y-axial direction;

a second displacement detecting portion for detecting displacements caused when the second masses are displaced in the Y-axial direction; and

an external force operation section for individually operating the angular velocity and the acceleration, using the displacements detected by the first and second displacement detecting portions.