Micromechanical gradient sensor

• US 6,244,111 B1
• Filed: 10/27/1999
• Issued: 06/12/2001
• Est. Priority Date: 10/30/1998
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Funk, Karsten
• Primary Examiner(s): Moller, Richard A.
• Application Number:
  US09/428,618
• Time in Patent Office: 594 Days
• Field of Search: 734/88, 735/040.2, 735/041.2
• US Class Current: 73/504.13
• CPC Class Codes: G01C 9/00 Measuring inclination, e.g. by clinometers, by levels

Abstract

A micromechanical gradient sensor having a substrate, a ring body which is mounted elastically above the substrate with the assistance of a first spring device, a driving device which is connected to the ring body for driving the ring body to rotary motions about the ring axis, and an acceleration sensing device which is secured to the ring body via a second spring device. The acceleration sensing device is designed in such a manner that, as a result of the centrifugal force acting due to the rotary motions, and as a result of the force acting against the spring tension of the two spring devices due to the gravitational acceleration, the acceleration sensing device is able to travel out along the sensor axis connecting it, and running through the ring axis. Also included is an evaluation unit for determining the excursion of the acceleration sensing device and for determining the angle of inclination of sensor axis relative to the perpendicular component.

Claims

1. A micromechanical inclination sensor comprising:

a substrate;

a first spring device;

a second spring device;

a ring body mounted elastically above the substrate via the first spring device;

a driving device connected to the ring body and for driving the ring body to undergo rotary motions about a ring axis;

said motions being in a plane parallel to the substrate;

an acceleration sensing device secured to the ring body via the second spring device, wherein;

the acceleration sensing device and the second spring device are formed such that an acceleration sensing axis is in the plane parallel to the substrate and running through the ring axis; and

an evaluation unit for measuring an excursion of the acceleration sensing device and for determining an angle of inclination of the sensor axis relative to the direction of gravity.

2. The micromechanical sensor according to claim 1, further comprising:

a control device for continually regulating the excursion to zero, wherein the angle of inclination of the sensor axis relative to the perpendicular component is ascertainable from a control signal produced by the control device.

3. The micromechanical sensor according to claim 1, further comprising:

a plurality of extension bars directed in a radially outwardly direction and provided on an outer periphery of the ring body, wherein the driving device includes;

a comb pattern of fixed capacitor plates and movable capacitor plates, the fixed capacitor plates being anchored to the substrate and the movable capacitor plates being attached to the plurality of extension bars.

4. The micromechanical sensor according to claim 1, further comprising:

a support pole provided on the substrate in the ring axis, wherein;

the first spring device includes a plurality of spring bars, and

the ring body is a circular ring body secured to the support pole via the plurality of spring bars.

5. The micromechanical sensor according to claim 4, wherein:

the plurality of spring bars includes four spring bars spaced apart from each other by 90°

.

6. The micromechanical sensor according to claim 1, wherein:

the acceleration sensing device includes at least one pair of mutually opposing acceleration sensors, the at least one pair of mutually opposing acceleration sensors being each secured to the ring body via the second spring device, each one of the at least one pair of mutually opposing acceleration sensors being capable of traveling out in a coupled fashion along the sensor axis connecting the acceleration sensors in the at least one pair and of running through the ring axis as a result of the centrifugal force acting due to the rotary motions, and as a result of the force acting against the spring tension of the first spring device and the spring tension of the second spring device due to the gravitational acceleration.

7. The micromechanical sensor according to claim 6, wherein:

the acceleration sensors include a plurality of frames, each of the plurality of frames being secured to the ring body tangentially via the second spring device,

a comb pattern of capacitor plates is formed in the plurality of frames, and

the comb pattern includes fixed capacitor plates anchored to the substrate and movable capacitor plates attached to the plurality of frames.

8. The micromechanical sensor according to claim 7, wherein the plurality of frames includes a plurality of U-frames.

9. The micromechanical sensor according to claim 7, wherein the second spring device includes a U-shaped double spring.

10. The micromechanical sensor according to claim 1, further comprising:

a plurality of support poles provided on the substrate, wherein;

the first spring device includes a plurality of spring bars,

the ring body is a circular ring body secured to a respective one of the plurality of support poles via the plurality of spring bars, and

each one of the plurality of support poles is provided as an extension of the plurality of spring bars.

11. The micromechanical sensor according to claim 10, wherein:

the plurality of spring bars includes four spring bars spaced apart from each other by 90°

.

12. The micromechanical sensor according to claim 10, wherein:

the second spring device includes a plurality of bar springs,

the acceleration sensing device includes an acceleration sensor arranged concentrically with respect to the ring body, and

the acceleration sensor includes;

a bar running in a direction of the sensor axis, the acceleration sensor being secured to an inner periphery of the ring body via the plurality of bar springs, and

a comb pattern of fixed capacitor plates anchored to the substrate and of movable capacitor plates attached to the bar.

13. The micromechanical sensor according to claim 12, wherein the plurality of bar springs includes four bar springs.

14. A micromechanical gradient sensor comprising:

a substrate;

a first spring device;

a second spring device;

a ring body mounted elastically above the substrate via the first spring device;

a driving device connected to the ring body and for driving the ring body to undergo rotary motions about a ring axis;

an acceleration sensing device secured to the ring body via the second spring device, wherein;

the acceleration sensing device is formed such that the acceleration sensing device is capable of traveling out along a sensor axis running through the ring axis as a result of a centrifugal force acting due to the rotary motions, and as a result of a force acting against a spring tension of the first spring device and a spring tension of the second spring device due to a gravitational acceleration; and

an evaluation unit for measuring the travel of the acceleration sensing device and for determining an angle of inclination of the sensor axis relative to a perpendicular component.

15. The micromechanical sensor according to claim 14, further comprising:

a control device for continually regulating the excursion to zero, wherein the angle of inclination of the sensor axis relative to the perpendicular component is ascertainable from a control signal produced by the control device.

16. The micromechanical sensor according to claim 14, further comprising:

a plurality of extension bars directed in a radially outwardly direction and provided on an outer periphery of the ring body, wherein the driving device includes;

a comb pattern of fixed capacitor plates and movable capacitor plates, the fixed capacitor plates being anchored to the substrate and the movable capacitor plates being attached to the plurality of extension bars.

17. The micromechanical sensor according to claim 14, further comprising:

a support pole provided on the substrate in the ring axis, wherein;

the first spring device includes a plurality of spring bars, and

the ring body is a circular ring body secured to the support pole via the plurality of spring bars.

18. The micromechanical sensor according to claim 17, wherein:

the plurality of spring bars includes four spring bars spaced apart from each other by 90°

.

19. The micromechanical sensor according to claim 14, wherein:

the acceleration sensing device includes at least one pair of mutually opposing acceleration sensors, the at least one pair of mutually opposing acceleration sensors being each secured to the ring body via the second spring device, each one of the at least one pair of mutually opposing acceleration sensors being capable of traveling out in a coupled fashion along the sensor axis connecting the acceleration sensors in the at least one pair and of running through the ring axis as a result of the centrifugal force acting due to the rotary motions, and as a result of the force acting against the spring tension of the first spring device and the spring tension of the second spring device due to the gravitational acceleration.

20. The micromechanical sensor according to claim 19, wherein:

the acceleration sensors include a plurality of frames, each of the plurality of frames being secured to the ring body tangentially via the second spring device,

a comb pattern of capacitor plates is formed in the plurality of frames, and

the comb pattern includes fixed capacitor plates anchored to the substrate and movable capacitor plates attached to the plurality of frames.

21. The micromechanical sensor according to claim 20, wherein the plurality of frames includes a plurality of U-frames.

22. The micromechanical sensor according to claim 20, wherein the second spring device includes a U-shaped double spring.

23. The micromechanical sensor according to claim 14, further comprising:

a plurality of support poles provided on the substrate, wherein;

the first spring device includes a plurality of spring bars,

the ring body is a circular ring body secured to a respective one of the plurality of support poles via the plurality of spring bars, and

each one of the plurality of support poles is provided as an extension of the plurality of spring bars.

24. The micromechanical sensor according to claim 23, wherein:

the plurality of spring bars includes four spring bars spaced apart from each other by 90°

.

25. The micromechanical sensor according to claim 23, wherein:

the second spring device includes a plurality of bar springs,

the acceleration sensing device includes an acceleration sensor arranged concentrically with respect to the ring body, and

the acceleration sensor includes;

a bar running in a direction of the sensor axis, the acceleration sensor being secured to an inner periphery of the ring body via the plurality of bar springs, and

a comb pattern of fixed capacitor plates anchored to the substrate and of movable capacitor plates attached to the bar.

26. The micromechanical sensor according to claim 25, wherein the plurality of bar springs includes four bar springs.