Angular velocity sensor

• US 20040173022A1
• Filed: 07/08/2003
• Published: 09/09/2004
• Est. Priority Date: 05/30/1995
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Uemura, Takeshi, Nozoe, Toshiyuki, Tamura, Masami
• Granted Patent: US 6,959,584 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719
• CPC Class Codes: G01P 21/02 of speedometers

Abstract

The present invention aims to present an angular velocity sensor having a self diagnosis function.

An angular velocity sensor of the present invention includes a driving part for stably vibrating a driving part of a sensor element having a driver part and a detector part for detecting an angular velocity and detection means for detecting the angular velocity of the sensor element and obtains a self diagnosis signal for a malfunction by detecting a mechanical coupling signal obtained at the detection means.

Claims

1. An angular velocity sensor comprising:

a sensor element including a vibrating part and a detector part for detecting an angular velocity;

a drive unit including a driver circuit and a monitor circuit, wherein said driver circuit supplies a driving signal to the vibrating part of said sensor element and wherein said monitor circuit receives a monitor signal outputted from said sensor element;

a detection unit including a pair of charging amplifiers or current amplifiers, a differential amplifier and a synchronous demodulator, wherein said pair of charging amplifiers or current amplifiers receive outputs from the detector part of said sensor element, said differential amplifier amplifies a difference in outputs from said pair of charging amplifiers or current amplifiers and wherein said synchronous demodulator detects an output from said differential amplifier in synchronous with the driving signal from said drive unit and outputs an angular velocity signal; and

a self diagnosis unit for outputting a diagnosis signal to detect an abnormality of said sensor element by coupling a signal synchronized with said driving signal to a circuit, said circuit having an output coupled to said synchronous demodulator.

4. An angular velocity sensor as recited in claim 1, wherein said signal synchronized with said driving signal is coupled to an input terminal of said pair of charging amplifiers or current amplifiers.

5. An angular velocity sensor as recited in claim 1, wherein said signal synchronized with said driving signal is an output from said monitor circuit.

6. An angular velocity sensor as recited in claim 1, wherein said self diagnosis unit comprises an attenuator and an injector, wherein said attenuator attenuates said signal synchronized with said driving signal and said injector injects the signal outputted from said attenuator to a circuit, said circuit having an output coupled to said synchronous demodulator.

8. An angular velocity sensor as recited in claim 6, wherein said injector comprises a capacitor.

10. An angular velocity sensor as recited in claim 6, wherein said injector comprises a resistor.

11. An angular velocity sensor as recited in claim 6, wherein said attenuator includes a ladder network resistor capable of digitally adjusting an amplitude and/or phase of an input signal.

12. An angular velocity sensor as recited in claim 1, further including a changing unit for changing said self diagnosis unit to either a working state or a non-working state.

13. An angular velocity sensor as recited in claim 12, wherein said changing unit is a switch for connecting or disconnecting, in accordance with an external handling, said signal synchronized with said driving signal to a circuit, said circuit having an output coupled to said synchronous demodulator.

14. An angular velocity sensor as recited in claim 12, wherein said changing unit comprises a timer circuit for connecting or disconnecting for a given time, in accordance with an external handling, said signal synchronized with said driving signal to a circuit, said circuit having an output coupled to said synchronous demodulator.

19. An angular velocity sensor as recited in claim 1, wherein said sensor element comprises vibrators composed of at least one of crystal, silicon, the combination of silicon and piezoelectric film and piezoelectric ceramic material.

38. An angular velocity sensor as recited in claim 6, further including a balancing unit, wherein said balancing unit is disposed at an input terminal of one of said pair of charging amplifiers or current amplifiers and said input terminal is not connected to said injector, in order to keep a balance of input characteristics between each of said pair of charging amplifiers or current amplifiers.

2. An angular velocity sensor comprising:

a sensor element including a vibrating part and a detector part for detecting an angular velocity;

a drive unit including a driver circuit and a monitor circuit, wherein said driver circuit supplies a driving signal to the vibrating part of said sensor element and wherein said monitor circuit receives a monitor signal outputted from said sensor element;

a detection unit including a pair of charging amplifiers or current amplifiers and a synchronous demodulator, wherein said pair of charging amplifiers or current amplifiers receive outputs from the detector part of said sensor element and wherein said synchronous demodulator sample-holds an output from said pair of charging amplifiers or current amplifiers in synchronous with the driving signal from said drive unit and outputs an angular velocity signal; and

a self diagnosis unit for outputting a diagnosis signal to detect an abnormality of said sensor element by coupling a signal synchronized with said driving signal to a circuit, said circuit having an output coupled to said synchronous demodulator.

15. An angular velocity sensor as recited in claim 2, further including a judge unit for continuously judging an abnormality of said sensor element by detecting an output signal level of said detection unit during a non-working state of said self diagnosis unit.

16. An angular velocity sensor as recited in claim 15, wherein said self diagnosis unit comprises an attenuator for attenuating said signal synchronized with said driving signal, and an injector for injecting a signal from said attenuator to a circuit, said circuit having an output coupled to said synchronous demodulator, wherein said changing unit is disposed between said attenuator and said injector.

17. An angular velocity sensor as recited in claim 15, wherein said changing unit is a switch for connecting or disconnecting, in accordance with an external handling, said signal synchronized with said driving signal to a circuit, said circuit having an output coupled to said synchronous demodulator.

18. An angular velocity sensor as recited in claim 15, wherein said changing unit comprises a timer circuit for connecting or disconnecting for a given time, in accordance with an external handling, said signal synchronized with said driving signal to a circuit, said circuit having an output coupled to said synchronous demodulator.

3. An angular velocity sensor comprising:

a sensor element including a vibrating part and a detector part for detecting an angular velocity;

a drive unit including a driver circuit and a monitor circuit, wherein said driver circuit supplies a driving signal to the vibrating part of said sensor element and wherein said monitor circuit receives a monitor signal outputted from said sensor element;

a detection unit including a pair of current amplifiers, a differential amplifier, a phase shifter and a synchronous detector, wherein said pair of current amplifiers receive outputs from the detector part of said sensor element, said differential amplifier amplifies a difference in outputs from said pair of current amplifiers, said phase shifter shifts the phase of an output of said differential amplifier by 90 degrees and wherein said synchronous detector detects an output from said phase shifter in synchronous with the driving signal from said drive unit and outputs an angular velocity signal; and

a self diagnosis unit for outputting a diagnosis signal to detect an abnormality of said sensor element by coupling a signal synchronized with said driving signal to a circuit, said circuit having an output coupled to said synchronous detector.

7. An angular velocity sensor comprising:

a sensor element including a driver part and a detector part for detecting an angular velocity;

a driver circuit for supplying a driving signal to the driver part of said sensor element, wherein a monitor signal is output from said sensor element and coupled to said driver circuit;

a detection unit including a charging amplifier and a synchronous detector, wherein an output from the detector part of said sensor element is applied to said charging amplifier, and wherein said synchronous detector receives both a signal synchronized with said driving signal and an output of said charging amplifier, said detection unit outputting an angular velocity signal; and

a self diagnosis unit for detecting an abnormality of said sensor element and outputting a self diagnosis signal by coupling said signal synchronized with said driving signal to an input of said synchronous detector,

wherein said self diagnosis unit comprises;

an attenuator for attenuating the signal synchronized with said driving signal and

a capacitor for injecting the signal synchronized with said driving signal from said attenuator to a circuit, said circuit having an output coupled to said synchronous detector.

9. An angular velocity sensor comprising:

a sensor element including a driver part and a detector part for detecting an angular velocity;

a driver circuit for supplying a driving signal to the driver part of said sensor element, wherein a monitor signal is output from said sensor element and coupled to said driver circuit;

a detection unit including a charging amplifier and a synchronous detector, wherein an output from the detector part of said sensor element is applied to said charging amplifier, and wherein said synchronous detector receives both a signal synchronized with said driving signal and an output of said charging amplifier, said detection unit outputting an angular velocity signal; and

a self diagnosis unit for detecting an abnormality of said sensor element and outputting a self diagnosis signal by coupling said signal synchronized with said driving signal to an input of said synchronous detector,

wherein said self diagnosis unit comprises;

an attenuator for attenuating the signal synchronized with said driving signal and

a resistor for injecting the signal synchronized with said driving signal from said attenuator to a circuit, said circuit having an output coupled to said synchronous detector.

20. An angular velocity sensor comprising:

a sensor element including a vibrating part and a detector part for detecting an angular velocity;

a drive unit including a driver circuit and a monitor circuit, wherein said driver circuit supplies a driving signal to the vibrating part of said sensor element and said monitor circuit receives a monitor signal outputted from said sensor element;

a detection unit including a pair of charging amplifiers or current amplifiers, a differential amplifier and a synchronous demodulator, wherein said pair of charging amplifiers or current amplifiers receive outputs from the detector part of said sensor element, said differential amplifier amplifies a difference in outputs from said pair of charging amplifiers or current amplifiers and wherein said synchronous demodulator detects an output from said differential amplifier in synchronous with the driving signal from said drive means and outputs an angular velocity signal; and

an adjusting unit for adjusting a signal from said detector part by coupling a signal synchronized with said driving signal to a circuit, said circuit having an output coupled to said synchronous demodulator, wherein said adjusting unit comprises an adjustor for varying said signal synchronized with said driving signal and an injector for injecting an output signal from said adjustor to a circuit, said circuit having an output coupled to said synchronous demodulator.

21. An angular velocity sensor as recited in claim 20, wherein said injector comprises a capacitor.

22. An angular velocity sensor as recited in claim 20, wherein said injector comprises a resistor.

23. An angular velocity sensor as recited in claim 20, wherein said adjustor includes a ladder network resistor capable of digitally adjusting an amplitude or phase of an input signal.

24. An angular velocity sensor as recited in claim 20, wherein said adjustor is capable of adjusting an offset of an output of said detection unit by adjusting an attenuation amount of the adjustor.

25. An angular velocity sensor as recited in claim 20, wherein said adjustor or injector includes a temperature sensitive element for compensating for temperature dependence of the signal synchronized with said driving signal.

26. An angular velocity sensor as recited in claim 20, further including a compensating unit for electrically compensating for an electrostatic coupling signal generated in an area around the vibrating part and detection part of said sensor element, by using a quasi-driving signal.

27. An angular velocity sensor as recited in claim 20, further including terminals to monitor the driving signal from said driver circuit and an output signal from the detection part of said sensor element for adjusting.

28. An angular velocity sensor as recited in claim 26, further including a stop unit for stopping the driving of said sensor element.

29. An angular velocity sensor comprising:

a sensor element including a vibrating part and a detector part for detecting an angular velocity;

a driver circuit supplying a driving signal to the vibrating part of said sensor element;

a monitor circuit receiving a monitor signal outputted from said sensor element;

a drive unit for generating stable self vibration in the vibrating part of said sensor element;

a control unit for stopping said self vibration;

a signal generator for applying an adjusting signal to the vibrating part of said sensor element during a working state of said control unit;

a pair of charging amplifiers or current amplifiers receiving an output from said detection part;

a detection unit including a synchronous demodulator, said synchronous demodulator demodulates an output from said pair of charging amplifiers or current amplifiers in synchronous with a driving signal from said drive unit and outputs an angular velocity signal; and

an adjusting unit for adjusting an electrostatic coupling signal generated in an area around the vibrating part and detection part of said sensor element by coupling a driving signal from said drive unit to a circuit, said circuit having an output coupled to said synchronous demodulator.

30. An angular velocity sensor as recited in claim 29, wherein said adjusting unit comprises an attenuator for adjusting a signal synchronized with said driving signal, and a capacitor for coupling an output signal from said attenuator to a circuit, said circuit having an output coupled to said synchronous demodulator.

31. An angular velocity sensor as recited in claim 29, wherein said control unit comprises a switch disposed in a loop of said drive unit.

32. An angular velocity sensor as recited in claim 29, wherein frequency of said adjusting signal from said signal generator differs from the frequency of characteristic vibration mode of said sensor element.

33. An angular velocity sensor as recited in claim 30, wherein said capacitor is integrated in a semiconductor integrated circuit, said integrated circuit comprises said drive unit and detection unit.

34. An angular velocity sensor as recited in claim 30, wherein said attenuator is capable of adjusting a level of attenuation.

35. An angular velocity sensor as recited in claim 30, wherein said attenuator comprises an amplifier having variable gain.

36. An angular velocity sensor as recited in claim 30, wherein said attenuator comprises a phase shifter having variable phase shift.

37. An angular velocity sensor as recited in claim 30, wherein said attenuator includes a digital adjusting unit, said digital adjusting unit is capable of adjusting the level of attenuation stepwise based on a predetermined digital data.

39. An angular velocity sensor as recited in claim 29, wherein said driver circuit includes a generation unit to generate a pair of signals for driving said sensor element, the phases of said pair of signals are inverse to each other, and wherein said sensor includes a selector for selecting either of said pair of signals and supplying it to said adjusting unit.

40. An angular velocity sensor as recited in claim 29, further including a selector, said selector selects either of said driving signal or monitor signal whereby the selected signal is supplied to said adjusting unit.

41. An angular velocity sensor comprising:

a sensor element including a driver part and a detector part;

a drive unit for supplying a driving signal to the driver part of said sensor element; and

a synchronous demodulator, wherein said synchronous demodulator detects an output from said detector part of said sensor element in synchronous with the driving signal from said drive unit, and outputs an angular velocity signal.

42. An angular velocity sensor of claim 41, further comprising:

a self diagnosis unit for outputting a diagnosis signal to detect an abnormality of said sensor element by coupling a signal synchronized with said driving signal to a circuit, said circuit having an output coupled to said synchronous demodulator.