Sensor-independent oscillation amplitude control

• US 20030151394A1
• Filed: 01/29/2003
• Published: 08/14/2003
• Est. Priority Date: 04/12/2000
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Bauer, Wolfram, Artzner, Johannes, Mohaupt, Jens
• Granted Patent: US 6,765,305 B2
• Time in Patent Office: Days
• US Class Current: 323/201
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

A device (100, 200) is described for generating an electric voltage by which a body of a capacitive and/or inductive sensor capable of vibration, such as a capacitive micromechanical rotational rate sensor in particular, is induced to vibrate.

In order to reduce the manufacturing cost of the sensor, a voltage generating device (109) is provided which induces a constant mechanical deflection of the body capable of vibration, this deflection being independent of the manufacturing tolerances of the sensor.

Claims

1. A device (100;

200) for generating an electric voltage whereby vibration of a body of a capacitive and/or inductive sensor capable of vibration, such as a capacitive micromechanical rotational rate sensor in particular, is induced,

characterized by a voltage generating device (109) which generates an electric voltage (U_I) which is proportional to the resting capacitance (C₀) and/or to the induction of the magnetic field of the sensor.

2. The device as recited in claim 1,

wherein the voltage generating device (109) forms part of a regulating circuit for regulating the amplitude of vibration of the body.

3. The device as recited in claim 1 or 2,

wherein the voltage generating device is a common-mode regulating apparatus (109) which responds only to common-mode signals at the input end.

4. The device as recited in claim 3,

wherein the common-mode regulating apparatus (109) has a first adder (120) and a regulator, preferably an I regulator, (119), and/or the output of the regulator (119) changes its voltage in regulating operation until virtually no common-mode signal is applied at the input of the regulator (109).

5. The device as recited in one of claims 1 through 4,

wherein the sensor (101) has two elements (102, 103) whose capacitance is variable over time in opposite directions, the two elements being formed in part by the body capable of vibration, and the change in capacitance of the elements (102, 103) being detected separately in a first and a second signal path (107, 108).

6. The device as recited in claim 5,

wherein the output signal of the adder (120) is sent to the input of the regulator (119), and a first input of the adder (120) picks up a first signal in the first signal path (107), and a second input of the adder (120) picks up a second signal in the second signal path (108).

7. The device as recited in claim 6,

wherein the output signal of the regulator (119) is sent to the input of a modulator (118) which modulates the output signal using the frequency (f_HF) of the voltage (U_HF) supplied to the elements (102, 103) and/or the output signal of the modulator (118) is sent to the first terminal of a first capacitor (116) having a first capacitance (C_I) and to the first terminal of a second capacitor (117) having a second capacitance (C_I) and/or the second terminal of the first capacitor (116) is electrically connected to the first signal path (107), and the second terminal of the second capacitor (117) is electrically connected to the second signal path (108).

8. The device as recited in claim 7,

wherein the output signal of the regulator (119) is sent to a first input of an amplifier (121) which amplifies a voltage (U_FE) applied to it by a factor (C_I/C₀) which depends on the particular sensor and is proportional to or equal to the quotient of the first capacitance (C_I) and the resting capacitance (C₀).

9. The device as recited in one of the preceding claims,

wherein the output signal of the first signal path (107) is sent to a first input of a second adder (110) and the output signal of the second signal path (108) is sent to a second input of the second adder (110), the output signal of the second adder (110) being demodulated by a demodulator (111) and sent to the amplifier (121) for amplification.

10. The device as recited in claim 9,

wherein the demodulator (111) performs a demodulation using the frequency (f_HF) of the voltage (U_HF) supplied to the elements (102, 103).

11. The device as recited in one of claims 1 through 10,

wherein the output voltage (U) of amplifier (121) is kept constant.

12. The device as recited in one of claims 2 through 7 or 9 through 10,

wherein the output voltage (U) of the amplifier (121) is proportional to the resting capacitance (C₀) of the sensor, and the electric voltage (U_I) is the reference variable of the regulating circuit for regulating the amplitude of vibration of the body capable of vibration.