Angular velocity sensor

• US 8,117,913 B2
• Filed: 08/07/2007
• Issued: 02/21/2012
• Est. Priority Date: 08/21/2006
• Status: Expired due to Fees

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Terada, Jirou
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US12/377,327
• Publication Number:
  US 20100218604A1
• Time in Patent Office: 1,659 Days
• Field of Search: 735/041.2, 735/041.5, 735/041.6, 735/040.4, 735/040.2, 735/041.4
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5726 Signal processing
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion
• CPC Class Codes: H10N 30/00 Piezoelectric or electrostrictive devices integrated devices or assemblies of multiple devices H10N39/00

Abstract

Disclosed is an angular velocity sensor for achieving downsizing of a variety of electronic devices. For this purpose, the angular velocity sensor has a subtracter for outputting a first differential signal based on two sensor signals output from a first sensing electrode unit and a second sensing electrode unit, an adder for outputting a first additional signal, another subtracter for outputting a second differential signal based on two sensor signals output from a third sensing electrode unit and a fourth sensing electrode unit, and another adder for outputting a second additional signal. The sensor then detects an angular velocity from an additional signal obtained based on the first differential signal and the second differential signal and a differential signal obtained based on the first additional signal and the second additional signal.

Claims

1. An angular velocity sensor comprising:

a sensing element including;

a plurality of arms;

a driver unit formed on one of the arms for driving the arm to vibrate; and

a first sensor unit and a second sensor unit formed on the arms for sensing distortion of the arms;

a driver circuit unit connected to the driver unit for driving the driver unit; and

a detector circuit unit connected to the first sensor unit and the second sensor unit for detecting an angular velocity,

wherein the driver circuit unit supplies two driving signals to the driver unit, and

wherein the detector circuit unit has functions of;

outputting a first differential signal according to two sensor signals output from the first sensor unit;

outputting a second differential signal according to two sensor signals output from the second sensor unit;

outputting a first additional signal according to the two sensor signals output from the first sensor unit;

outputting a second additional signal according to the two sensor signals output from the second sensor unit; and

detecting the angular velocity from an additional signal obtained based on the first differential signal and the second differential signal, and a differential signal obtained based on the first additional signal and the second additional signal.

2. The angular velocity sensor of claim 1 further comprising:

a failure diagnosis unit for supplying two failure diagnosis signals of same phase or opposite phase to the driver unit, and detecting a pseudo angular velocity from the additional signal and the differential signal.

3. The angular velocity sensor of claim 2, wherein the driving signals and the failure diagnosis signals have waveforms different in phase by 90 degrees with respect to each other.

4. An angular velocity sensor comprising:

a sensing element including;

a plurality of arms;

a driver unit formed on one of the arms for driving the arm to vibrate; and

a first sensor unit and a second sensor unit formed on the arms for sensing distortion of the arms;

a driver circuit unit connected to the driver unit for driving the driver unit; and

a detector circuit unit connected to the first sensor unit and the second sensor unit for detecting an angular velocity,

wherein the driver circuit unit supplies two driving signals to the driver unit,

wherein the detector circuit unit has functions of;

outputting a first differential signal according to two sensor signals output from the first sensor unit;

outputting a second differential signal according to two sensor signals output from the second sensor unit;

outputting a first additional signal according to the two sensor signals output from the first sensor unit;

outputting a second additional signal according to the two sensor signals output from the second sensor unit; and

detecting the angular velocity from an additional signal obtained based on the first differential signal and the second differential signal, and a differential signal obtained based on the first additional signal and the second additional signal,

wherein the plurality of arms includes;

two orthogonally-configured arms, each consisting of a first arm coupled to a second arm in a direction generally orthogonal to each other,

a supporting portion supporting the two first arms,

a fixing arm connected to the supporting portion and fixed to a mount board, and

weights provided at respective ends of the second arms;

wherein the two second arms are configured to confront each other, and

the first sensor unit is formed on one of the second arms and the second sensor unit is formed on the other of the second arms.

5. The angular velocity sensor of claim 4,

wherein the first sensor unit includes a first sensing electrode unit and a second sensing electrode unit, each having a top electrode and a bottom electrode with a piezoelectric element interposed therebetween;

the second sensor unit includes a third sensing electrode unit and a fourth sensing electrode unit, each having a top electrode and a bottom electrode with a piezoelectric element interposed therebetween;

the first sensing electrode unit and the second sensing electrode unit are formed on one of the second arms in a confronting manner, and output two sensor signals; and

the third sensing electrode unit and the fourth sensing electrode unit are formed on the other of the second arms in a confronting manner, and output two sensor signals.