Inertial force sensor

• US 8,397,569 B2
• Filed: 04/08/2009
• Issued: 03/19/2013
• Est. Priority Date: 04/10/2008
• Status: Expired due to Fees

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kuroda, Keisuke, Uemura, Takeshi
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): Shah, Samir M
• Application Number:
  US12/936,446
• Publication Number:
  US 20110041607A1
• Time in Patent Office: 1,441 Days
• Field of Search: 735/041.2, 735/81, 735/141.6, 735/143.5, 702/41
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38

Abstract

An inertial force sensor which reduces the deterioration of an angular speed detection accuracy and improves the diagnosis accuracy of fault diagnosis is provided.

The inertial force sensor includes an oscillator having a driving electrode, a monitor electrode, and a detecting electrode; a driving circuit which applies a driving signal to the driving electrode to oscillate the oscillator; a detecting circuit which detects an angular speed according to a detecting signal outputted from the detecting electrode due to an inertial force; an oscillation control circuit which controls an energization amount of the driving signal according to a monitor signal outputted from the monitor electrode; and a fault diagnosing circuit which inputs a pseudo angular speed signal to the detecting circuit for fault diagnosis, wherein a filter switching circuit which switches a characteristic of a filter circuit included in the detecting circuit in fault diagnosis mode to shorten a delay time is provided.

Claims

1. An inertial force sensor comprising:

an oscillator having a driving electrode, a monitor electrode, and a detecting electrode;

a driving circuit configured to apply a driving signal to the driving electrode to oscillate the oscillator;

a detecting circuit configured to detect an angular speed according to a detecting signal outputted from the detecting electrode due to an inertial force in a normal mode, the detecting circuit has a filter circuit which filters the detecting signal;

an oscillation control circuit configured to control an energization amount of the driving signal according to a monitor signal outputted from the monitor electrode; and

a fault diagnosing circuit, wherein

when in a fault diagnosis mode,

the detecting circuit is configured to switch a cutoff frequency of the filter circuit in the fault diagnosis mode higher than the cutoff frequency in the normal mode, and the fault diagnosing circuit is configured to input a pseudo angular speed signal to the detecting circuit for fault diagnosis after switching the cutoff frequency of the filter circuit.

2. The inertial force sensor according to claim 1, wherein the cutoff frequency of the filter circuit is determined according to a clock frequency.

3. The inertial force sensor according to claim 1, wherein responsibility of the filter circuit is determined according to a clock frequency and the fault diagnosing circuit performs fault diagnosis by making the clock frequency in the fault diagnosis mode higher than the clock frequency in the normal mode.

4. The inertial force sensor according to claim 2 or 3, wherein fault diagnosis is performed only at the time of start.

5. The inertial force sensor according to claim 2 or 3, wherein fault diagnosis is performed at either the time of start or the time of stable driving.

6. An inertial force sensor comprising:

an oscillator having a driving electrode, a monitor electrode, and a detecting electrode;

a driving circuit configured to apply a driving signal to the driving electrode to oscillate the oscillator;

a detecting circuit configured to detect an angular speed according to a detecting signal outputted from the detecting electrode due to an inertial force in a normal mode, the detecting circuit has a filter circuit which filters the detecting signal;

an oscillation control circuit configured to control an energization amount of the driving signal according to a monitor signal outputted from the monitor electrode; and

a fault diagnosing circuit, wherein

when in a fault diagnosis mode,

the detecting circuit is configured to switch a delay time of the filter circuit in the fault diagnosis mode lower than the delay time in the normal mode, and the fault diagnosing circuit is configured to input a pseudo angular speed signal to the detecting circuit for fault diagnosis after switching the delay time of the filter circuit to be lower.

7. The inertial force sensor according to claim 6, wherein responsibility of the filter circuit is determined according to a clock frequency and the fault diagnosing circuit performs fault diagnosis by making the clock frequency in the fault diagnosis mode higher than the clock frequency in the normal mode.