Dynamic amount sensor

• US 20070240509A1
• Filed: 02/06/2007
• Published: 10/18/2007
• Est. Priority Date: 02/14/2006
• Status: Active Grant

• Current Assignee: Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Egawa, Akira, Uchiyama, Takeshi, Yarita, Mitsuo
• Granted Patent: US 7,886,597 B2
• Time in Patent Office: Days
• US Class Current: 73/514.320
• 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: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0842 the mass being of clover leaf shape

Abstract

It is an object of the invention to promote a detection sensitivity by effectively utilizing an arranged fixed electrode. Inclinations in x-axis and y-axis directions of a mass are detected in a two-axis detecting circuit. The two-axis detecting circuit is constituted by fixed electrodes having both of an x-axis detecting circuit function and a y-axis detecting circuit function and also having functions for detecting displacements in an x-axis direction and a y-axis direction. The two-axis detecting circuit switches the x-axis detecting circuit function and the y-axis detecting circuit function by switching wirings in the circuit by way of a switching circuit. Switching of a wiring state of the two-axis detecting circuit is carried out at each constant period based on a timing of a specific clock signal. In this way, the fixed electrodes can be used in both of the two circuit functions, and therefore, components in respective axes directions of an angular velocity can be detected based on a total sum of electrode sensitivities of the fixed electrodes. Thereby, a detection sensitivity can be promoted without increasing a sensor size, or increasing electrodes for detection.

Claims

1. A dynamic amount sensor comprising:

a frame having a hollow portion;

a beam having a flexibility fixed to the frame;

a mass which is supported by the frame by way of the beam, a surface portion of which functions as a movable electrode, and an attitude of which is changed by an operation of an external force;

a plurality of fixed electrodes which is arranged to face the mass in an opposed manner;

detecting means for detecting a change in an electrostatic capacitance of an electrostatic capacitance element comprising the movable electrode and the fixed electrode;

switching means for switching the detecting means to a connecting state of a first detecting circuit for detecting the change in the electrostatic capacitance of the electrostatic capacitance element in accordance with a change in an attitude in a first detecting axis direction of the mass and a connecting state of a second detecting circuit for detecting the change in the electrostatic capacitance of the electrostatic capacitance element in accordance with a change in an attitude in a second detecting axis direction of the mass by switching a wire connecting state of the electrostatic capacitance element; and

dynamic amount outputting means for outputting a first detecting axis direction component and a second detecting axis direction component of an operated dynamic amount based on a result of detection of the detecting means.

2. The dynamic amount sensor according to claim 1, wherein the switching means switches the detecting means to the connecting state of the first detecting circuit, the connecting state of the second detecting circuit, and a connecting state of a third detecting circuit for detecting the change in the electrostatic capacitance of the electrostatic capacitance element in accordance with a change in a third detecting axis direction of the mass by switching the wire connecting state of the electrostatic capacitance element;

and

wherein the dynamic amount outputting means outputs the first detecting axis direction component, the second detecting axis direction component, and a third detecting axis direction component of the operated dynamic amount based on the result of detection of the detecting means.

3. The dynamic amount sensor according to claim 1, wherein the switching means switches wire connecting states of the electrostatic capacitance elements at each constant period based on timings of a control clock signal;

wherein output signals of the detecting means are inputted to the same amplifying circuit; and

wherein the dynamic amount outputting means outputs the dynamic amount operated in respective axes directions of the mass after separating detecting signals of the electrostatic capacitances of the respective detecting circuits by carrying out a time division processing based on the switching timings by the switching means.

4. The dynamic amount sensor according to claim 2, wherein the switching means switches wire connecting states of the electrostatic capacitance elements at each constant period based on timings of a control clock signal;

wherein output signals of the detecting means are inputted to the same amplifying circuit; and

wherein the dynamic amount outputting means outputs the dynamic amount operated in respective axes directions of the mass after separating detecting signals of the electrostatic capacitances of the respective detecting circuits by carrying out a time division processing based on the switching timings by the switching means.

5. The dynamic amount sensor according to claim 1, wherein the first detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the first detecting axis direction of the mass;

wherein the second detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the second detecting axis direction of the mass; and

wherein respectives of the electrostatic capacitance elements connected in series of the first detecting circuit and the second detecting circuit include carrier wave applying means for applying carrier waves phases of which are inverted from each other by 180°

.

6. The dynamic amount sensor according to claim 2, wherein the first detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the first detecting axis direction of the mass;

wherein the second detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the second detecting axis direction of the mass; and

wherein respectives of the electrostatic capacitance elements connected in series of the first detecting circuit and the second detecting circuit include carrier wave applying means for applying carrier waves phases of which are inverted from each other by 180°

.

7. The dynamic amount sensor according to claim 3, wherein the first detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the first detecting axis direction of the mass;

wherein the second detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the second detecting axis direction of the mass; and

wherein respectives of the electrostatic capacitance elements connected in series of the first detecting circuit and the second detecting circuit include carrier wave applying means for applying carrier waves phases of which are inverted from each other by 180°

.

8. The dynamic amount sensor according to claim 4, wherein the first detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the first detecting axis direction of the mass;

wherein the second detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the second detecting axis direction of the mass; and

wherein respectives of the electrostatic capacitance elements connected in series of the first detecting circuit and the second detecting circuit include carrier wave applying means for applying carrier waves phases of which are inverted from each other by 180°

.

9. The dynamic amount sensor according to claim 5, wherein the third detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the third detecting axis direction of the mass;

and

wherein the carrier wave applying means includes carrier wave applying means for applying carrier waves phases of which are inverted from each other by 180°

to respectives of the electrostatic capacitance elements connected in series of the third detecting circuit.

10. The dynamic amount sensor according to claim 6, wherein the third detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the third detecting axis direction of the mass;

and

wherein the carrier wave applying means includes carrier wave applying means for applying carrier waves phases of which are inverted from each other by 180°

to respectives of the electrostatic capacitance elements connected in series of the third detecting circuit.

11. The dynamic amount sensor according to claim 7, wherein the third detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the third detecting axis direction of the mass;

and

wherein the carrier wave applying means includes carrier wave applying means for applying carrier waves phases of which are inverted from each other by 180°

to respectives of the electrostatic capacitance elements connected in series of the third detecting circuit.

12. The dynamic amount sensor according to claim 8, wherein the third detecting circuit includes a circuit connected in series with the electrostatic capacitance elements electrostatic capacitances of which are symmetrically changed in accordance with an inclination in the third detecting axis direction of the mass;

and

wherein the carrier wave applying means includes carrier wave applying means for applying carrier waves phases of which are inverted from each other by 180°

to respectives of the electrostatic capacitance elements connected in series of the third detecting circuit.

13. The dynamic amount sensor according to claim 1, wherein the fixed electrode includes four of first electrodes constituting a reference position by a center position of the mass and arranged at equal intervals around the reference position on the same plane;

wherein the first detecting circuit includes a circuit connected in series with a circuit connected in parallel with the electrostatic capacitance element constituted by the first electrode disposed in a first quadrant on an x-y plane of the four first electrodes and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in a second quadrant and the movable electrode, and a circuit connected in parallel with the electrostatic capacitance element constituted by the first electrode disposed in a fourth quadrant on the x-y plane of the four first electrodes and the movable electrode and the electrostatic capacitance element constituted by the first electrode disposed in a third quadrant and the movable electrode;

wherein the second detecting circuit includes a circuit connected in series with a circuit connected in parallel with the electrostatic capacitance element constituted by the first electrode disposed in the first quadrant on the x-y plane of the four first electrodes and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the fourth quadrant and the movable electrode, and a circuit connected in parallel with the electrostatic capacitance element constituted by the first electrode disposed in the third quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the second quadrant and the movable electrode; and

wherein the switching means switches the wire connecting states of the electrostatic capacitance elements such that the detecting means constitutes the first detecting circuit or the second detecting circuit.

14. The dynamic amount sensor according to claim 2, wherein the fixed electrode includes four of first electrodes constituting a reference position by a center position of the mass and arranged at equal intervals around the reference position on the same plane;

wherein the first detecting circuit includes a circuit connected in series with a circuit connected in parallel with the electrostatic capacitance element constituted by the first electrode disposed in a first quadrant on an x-y plane of the four first electrodes and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in a second quadrant and the movable electrode, and a circuit connected in parallel with the electrostatic capacitance element constituted by the first electrode disposed in a fourth quadrant on the x-y plane of the four first electrodes and the movable electrode and the electrostatic capacitance element constituted by the first electrode disposed in a third quadrant and the movable electrode;

wherein the second detecting circuit includes a circuit connected in series with a circuit connected in parallel with the electrostatic capacitance element constituted by the first electrode disposed in the first quadrant on the x-y plane of the four first electrodes and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the fourth quadrant and the movable electrode, and a circuit connected in parallel with the electrostatic capacitance element constituted by the first electrode disposed in the third quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the second quadrant and the movable electrode; and

wherein the switching means switches the wire connecting states of the electrostatic capacitance elements such that the detecting means constitutes the first detecting circuit or the second detecting circuit.

15. The dynamic amount sensor according to claim 13, wherein the fixed electrode further includes four of second electrodes on a plane opposed to the four first electrodes by way of the mass;

wherein the first detecting circuit includes a circuit connected in parallel with the electrostatic capacitance element constituted by the second electrode disposed in the fourth quadrant on the x-y plane of the four second electrodes and the movable electrode, and the electrostatic capacitance element constituted by the second electrode disposed in the third quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the first quadrant on the x-y plane and the movable electrode, further, connected in parallel with the electrostatic capacitance element constituted by the second electrode disposed in the first quadrant on the x-y plane of the four second electrodes and the movable electrode, and the electrostatic capacitance element constituted by the second electrode disposed in the second quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the third quadrant on the x-y plane and the movable electrode; and

wherein the second detecting circuit includes a circuit connected in parallel with the electrostatic capacitance element constituted by the second electrode disposed in the first quadrant on the x-y plane of the four second electrodes and the movable electrode, and the electrostatic capacitance element constituted by the second electrode disposed in the fourth quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the third quadrant on the x-y plane and the movable electrode, further, connected in parallel with the electrostatic capacitance element constituted by the second electrode disposed in the third quadrant on the x-y plane of the four second electrodes and the movable electrode, and the electrostatic capacitance element constituted by the second electrode disposed in the second quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the first quadrant on the x-y plane and the movable electrode.

16. The dynamic amount sensor according to claim 14, wherein the fixed electrode further includes four of second electrodes on a plane opposed to the four first electrodes by way of the mass;

wherein the first detecting circuit includes a circuit connected in parallel with the electrostatic capacitance element constituted by the second electrode disposed in the fourth quadrant on the x-y plane of the four second electrodes and the movable electrode, and the electrostatic capacitance element constituted by the second electrode disposed in the third quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the first quadrant on the x-y plane and the movable electrode, further, connected in parallel with the electrostatic capacitance element constituted by the second electrode disposed in the first quadrant on the x-y plane of the four second electrodes and the movable electrode, and the electrostatic capacitance element constituted by the second electrode disposed in the second quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the third quadrant on the x-y plane and the movable electrode; and

wherein the second detecting circuit includes a circuit connected in parallel with the electrostatic capacitance element constituted by the second electrode disposed in the first quadrant on the x-y plane of the four second electrodes and the movable electrode, and the electrostatic capacitance element constituted by the second electrode disposed in the fourth quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the third quadrant on the x-y plane and the movable electrode, further, connected in parallel with the electrostatic capacitance element constituted by the second electrode disposed in the third quadrant on the x-y plane of the four second electrodes and the movable electrode, and the electrostatic capacitance element constituted by the second electrode disposed in the second quadrant on the x-y plane and the movable electrode, and the electrostatic capacitance element constituted by the first electrode disposed in the first quadrant on the x-y plane and the movable electrode.

17. The dynamic amount sensor according to claim 13, wherein the fixed electrode further includes a third electrode on the plane opposed to the four first electrodes by way of the mass;

and

wherein the third detecting circuit includes a circuit connected in series with the electrostatic capacitance element constituted by the first electrode and the movable electrode and the electrostatic capacitance element constituted by the third electrode and the movable electrode.

18. The dynamic amount sensor according to claim 14, wherein the fixed electrode further includes a third electrode on the plane opposed to the four first electrodes by way of the mass;

and

wherein the third detecting circuit includes a circuit connected in series with the electrostatic capacitance element constituted by the first electrode and the movable electrode and the electrostatic capacitance element constituted by the third electrode and the movable electrode.

19. The dynamic amount sensor according to claim 3, wherein the dynamic amount outputting means separates detecting signals of the electrostatic capacitances of the respective detecting circuits after an elapse of a predetermined time period from a timing of switching connection by the switching means.

20. The dynamic amount sensor according to claim 19, wherein the predetermined time period is provided within a range of 3 through 4 τ

from the timing of switching the connection by the switching means.