APPARATUS AND METHOD FOR DRIVING INERTIAL SENSOR

• US 20120285244A1
• Filed: 05/04/2012
• Published: 11/15/2012
• Est. Priority Date: 05/13/2011
• Status: Active Grant

• Current Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Original Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Inventors: Kim, Chang Hyun
• Granted Patent: US 8,978,471 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices

Abstract

Disclosed herein are an apparatus and a method for driving an inertial sensor. The apparatus for driving an inertial sensor includes a detection unit that detects first acceleration detection voltage and detects angular velocity detection voltage when a wake up signal is input; a wake up signal generation unit that generates the wake up signal when the total of acceleration detection voltage is larger than predetermined voltage; a phase conversion unit that generates driving voltage and inversion driving voltage of the corresponding axis; a driving unit that vibrates the inertial sensor; and a control unit that performs a control to wake up the detection unit, the phase conversion unit, and the driving unit or convert them into a sleep mode according to a control signal, whereby power consumption can be minimized in an apparatus requiring low power like mobile environment.

Claims

1. An apparatus for driving an inertial sensor, comprising:

a detection unit that detects first acceleration detection voltage corresponding to acceleration of each axis of the inertial sensor and detects angular velocity detection voltage corresponding to angular velocity of each axis of the inertial sensor when a wake up signal is input;

a wake up signal generation unit that generates the wake up signal when second acceleration detection voltage calculated from the first acceleration detection voltage of each axis is larger than predetermined reference voltage;

a phase conversion unit that generates driving voltage and inversion driving voltage of the corresponding axis by shifting the first acceleration detection voltage of each axis by a predetermined phase so as to vibrate the inertial sensor in directions of each axis when the wake signal is input;

a driving unit that provides the driving voltage and the inversion driving voltage of the corresponding axis to corresponding driving electrodes when the wake up signal is input so as to vibrate the inertial sensor in the directions of the corresponding axis; and

a control unit that performs a control to wake up the detection unit, the phase conversion unit, and the driving unit or convert the detection unit, the phase conversion unit, and the driving unit into a sleep mode according to a control signal.

2. The apparatus for driving an inertial sensor as set forth in claim 1, wherein the detection unit includes:

a first detector that detects the first acceleration detection voltage corresponding to the acceleration of each axis due to the deformations caused by linear motions of each axis of the inertial sensor;

a second detector that detects angular velocity detection voltage corresponding to the angular velocity of each axis due to the deformations caused by Coriolis force and vibrations of each axis of the inertial sensor when the wake up signal is input; and

a switching unit that is switched to disconnect the first detector from the second detector according to a control signal when the wake up signal of the control unit is absent and to connect the first detector to the second detector according to the control signal when the wake up signal of the control unit is present.

3. The apparatus for driving an inertial sensor as set forth in claim 2, wherein the first detector includes:

a first detection amplifier that amplifies output voltage from a positive detection electrode disposed on a first axis of the inertial sensor;

a second detection amplifier that amplifies output voltage from a negative detection electrode disposed on the first axis of the inertial sensor;

a third detection amplifier that amplifies output voltage from a positive detection electrode disposed on a second axis of the inertial sensor;

a fourth detection amplifier that amplifies output voltage from a negative detection electrode disposed on the second axis of the inertial sensor;

a first detection subtracter that outputs the first acceleration detection voltage of the first axis corresponding to the first axis acceleration calculated by subtracting the output voltage from the second detection amplifier from the output voltage from the first detection amplifier;

a second detection subtracter that outputs the first acceleration detection voltage of the second axis corresponding to the second axis acceleration calculated by subtracting the output voltage from the fourth detection amplifier from the output voltage from the third detection amplifier; and

a first detection adder that outputs the first acceleration detection voltage of a third axis corresponding to the third axis acceleration calculated by adding the output voltage from the first detection amplifier, the output voltage from the second detection amplifier, the output voltage from the third detection amplifier, and the output voltage from the fourth amplifier.

4. The apparatus for driving an inertial sensor as set forth in claim 3, wherein the second detector includes:

a first detection multiplier that outputs the second axis angular velocity detection voltage corresponding to the second axis angular velocity calculated by multiplying the first acceleration detection voltage of the first axis re-detected through the first detector by the third axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the third axis according to the third axis driving voltage for vibrating the inertial sensor in a direction of the third axis;

a second detection multiplier that outputs the first axis angular velocity detection voltage corresponding to the first axis angular velocity calculated by multiplying the first acceleration detection voltage of the second axis re-detected through the first detector by the third axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the third axis according to the third axis driving voltage for vibrating the inertial sensor in a direction of the third axis; and

a third detection multiplier that outputs the second axis angular velocity detection voltage corresponding to the second axis angular velocity calculated by multiplying the first acceleration detection voltage of the third axis re-detected through the first detector by the first axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the first axis according to the first axis driving voltage for vibrating the inertial sensor in a direction of the first axis.

5. The apparatus for driving an inertial sensor as set forth in claim 4, wherein the first detection multiplier outputs third axis angular velocity detection voltage corresponding to the third axis angular velocity calculated by multiplying the first acceleration detection voltage of the first axis re-detected through the first detector by the second axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the second axis according to the second axis driving voltage for vibrating the inertial sensor in a direction of the second axis.

6. The apparatus for driving an inertial sensor as set forth in claim 4, wherein the second detection multiplier outputs the third axis angular velocity detection voltage corresponding to the third axis angular velocity calculated by multiplying the first acceleration detection voltage of the second axis re-detected through the first detector by the first axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the first axis according to the first axis driving voltage for vibrating the inertial sensor in a direction of the first axis.

7. The apparatus for driving an inertial sensor as set forth in claim 4, wherein the third detection multiplier outputs the first axis angular velocity detection voltage corresponding to the first axis angular velocity calculated by multiplying the first acceleration detection voltage of the third axis re-detected through the first detector by the second axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the second axis according to the second axis driving voltage for vibrating the inertial sensor in the direction of the second axis.

8. The apparatus for driving an inertial sensor as set forth in claim 4, wherein the switching unit includes:

a first switch stage that is switched to disconnect or connect the first detection subtracter from or to the first detection multiplier according to the control signal of the control unit;

a second switch stage that is switched to disconnect or connect the second detection subtracter from or to the second detection multiplier according to the control signal of the control unit; and

a third switch stage that is switched to disconnect or connect the first detection adder from or to the third detection multiplier according to the control signal of the control unit.

9. The apparatus for driving an inertial sensor as set forth in claim 1, wherein the wake up signal generation unit includes:

a second detection adder that outputs the second acceleration detection voltage calculated by adding the first acceleration detection voltage of each axis detected through the detection unit;

a high frequency filter that is filtered to remove high frequency signals in order to remove noise from the output second acceleration detection voltage; and

a comparator that generates the wake up signals when the second acceleration detection voltage is larger than the reference voltage by comparing the filtered second acceleration detection voltage with the reference voltage.

10. The apparatus for driving an inertial sensor as set forth in claim 1, wherein the driving unit includes:

a first driving amplifier that amplifies the first axis driving voltage or the third axis driving voltage generated from the phase conversion unit and provides the amplified first axis driving voltage or the amplified third axis driving voltage to a positive driving electrode disposed on the first axis of the inertial sensor;

a second driving amplifier that amplifies the first axis inversion driving voltage or the third axis inversion driving voltage generated from the phase conversion unit and provides the amplified first axis inversion driving voltage or the amplified inversion third axis driving voltage to a negative driving electrode disposed on the first axis of the inertial sensor;

a third driving amplifier that amplifies the second axis driving voltage or the third axis driving voltage generated from the phase conversion unit and provides the amplified second axis driving voltage or the amplified third axis driving voltage to a positive driving electrode disposed on the second axis of the inertial sensor; and

a fourth driving amplifier that amplifies the second axis inversion driving voltage or the third axis inversion driving voltage generated from the phase conversion unit and provides the amplified second axis driving voltage or the amplified third axis driving voltage to a negative driving electrode disposed on the second axis of the inertial sensor.

11. The apparatus for driving an inertial sensor as set forth in claim 2, wherein the control unit turns-off the switching unit according to the control signal when the wake up signal is absent if the angular velocity detection voltage of each axis detected from the second detector is absent for the predetermined time to perform a control to convert the second detector, the phase conversion unit, and the driving unit into a sleep mode.

12. A method for driving an inertial sensor, comprising:

(A) detecting first acceleration detection voltage corresponding to acceleration of each axis of an inertial sensor by a first detector;

(B) generating a wake up signal by a wake up signal generation unit when second acceleration detection voltage calculated from the first acceleration detection voltage of each axis is larger than predetermined reference voltage; and

(C) detecting angular velocity detection voltage corresponding to angular velocity of each axis of the inertial sensor by the woken up second detector, the phase conversion unit, and the driving unit by receiving the wake up signal.

13. The method for driving an inertial sensor as set forth in claim 12, further comprising:

(D) converting the second detector, the phase conversion unit, and the driving unit to be in a sleep mode by the control unit when the angular velocity detection voltage of each axis is not detected for the predetermined time.

14. The method for driving an inertial sensor as set forth in claim 12, wherein the (A) includes:

(A-1) amplifying first output voltage from a positive detection electrode and second output voltage from a negative detection electrode disposed on a first axis of the inertial sensor by the first detector and then, outputting first acceleration detection voltage of a first axis due to the deformations caused by a linear motion of the first axis by subtracting the amplified second output voltage from the amplified first output voltage;

(A-2) amplifying third output voltage from a positive detection electrode and fourth output voltage from a negative detection electrode disposed on a second axis of the inertial sensor by the first detector and then, outputting first acceleration detection voltage of a second axis due to the deformations caused by a linear motion of the second axis by subtracting the amplified fourth output voltage from the amplified third output voltage; and

(A-3) adding the amplified first output voltage, the amplified second output voltage, the amplified third output voltage, and the amplified fourth output voltage by the first detector to output the first acceleration detection voltage of a third axis due to the deformations caused by a linear motion of the third axis of the inertial sensor.

15. The method for driving an inertial sensor as set forth in claim 12, wherein the (B) includes:

(B-1) calculating second acceleration detection voltage by adding the first acceleration detection voltage of each axis;

(B-2) determining whether the calculated second acceleration detection voltage is larger than the reference voltage; and

(B-3) generating a wake up signal when the second acceleration detection voltage is larger than the reference voltage.

16. The method for driving an inertial sensor as set forth in claim 12, wherein the (C) includes:

(C-1) generating driving voltage and inversion driving voltage of the corresponding axis by shifting the first acceleration detection voltage of each axis by a predetermined phase so as to vibrate the inertial sensor in directions of each axis by the phase conversion unit when the wake up signal is input;

(C-2) vibrating the inertial sensor in the direction of the corresponding axis by providing the driving voltage and the inversion driving voltage of the corresponding axis to the corresponding driving voltage through the driving unit when the wake up signal is input; and

(C-3) detecting angular velocity detection voltage corresponding to angular velocity of each axis due to deformations caused by Coriolis force and vibrations of the corresponding axis of the inertial sensor by a second detector when the wake up signal is input.

17. The method for driving an inertial sensor as set forth in claim 16, wherein the (C-3) includes:

outputting the second axis angular velocity detection voltage corresponding to the second axis angular velocity calculated by multiplying the first acceleration detection voltage of the first axis re-detected through the first detector by the third axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the third axis according to the third axis driving voltage of the inertial sensor;

outputting the first axis angular velocity detection voltage corresponding to the first axis angular velocity calculated by multiplying the first acceleration detection voltage of the second axis re-detected through the first detector by the third axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the third axis according to the third axis driving voltage of the inertial sensor; and

outputting the third axis angular velocity detection voltage corresponding to the third axis angular velocity calculated by multiplying the first acceleration detection voltage of the first axis re-detected through the first detector by the second axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the second axis according to the second axis driving voltage of the inertial sensor.

18. The method for driving an inertial sensor as set forth in claim 17, wherein the (C-3) includes:

outputting the second axis angular velocity detection voltage corresponding to the second axis angular velocity calculated by multiplying the first acceleration detection voltage of the third axis re-detected through the first detector by the first axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the first axis according to the first axis driving voltage of the inertial sensor;

outputting the third axis angular velocity detection voltage corresponding to the third axis angular velocity calculated by multiplying the first acceleration detection voltage of the second axis re-detected through the first detector by the first axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the first axis according to the first axis driving voltage of the inertial sensor; and

outputting the first axis angular velocity detection voltage corresponding to the first axis angular velocity calculated by multiplying the first acceleration detection voltage of the third axis re-detected through the first detector by the second axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the second axis according to the second axis driving voltage of the inertial sensor.