Angular velocity sensor

Details Angular velocity sensor Angular velocity sensor

1999-06-14

2001-06-12

Moller, Richard A. (Department: 2856)

Measuring and testing

Instrument proving or calibrating

Apparatus for measuring by use of vibration or apparatus for...

C073S504020

Reexamination Certificate

active

06244095

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an angular velocity sensor having a self diagnosis function.
BACKGROUND OF THE INVENTION
A conventional tuning fork type, angular velocity sensor has detector plates at the top of two driver plates of the tuning fork type driving part facing in the orthogonal direction. When an angular velocity is applied at a continuous driving state of the driving part, the angular velocity is detected by the output of the detector plates vibrating in opposite direction to each other corresponding to the applied angular velocity.
In an angular velocity sensor in accordance with the prior art, a tightly sealed space is formed by a lid
2
, which is made of resin. Lid
2
is attached at an aperture of a case
1
, also made of resin, of which one end is open, as shown in FIG.
18
.
Inside the tightly sealed space, a circuit board
3
and a metallic weight plate
4
are contained. Supporting pins
5
are attached at four corners inside the case
1
and weight plate
4
and circuit board
3
are elastically supported and fixed by the supporting pins
5
. Dampers
6
made of rubber are attached at the four corners of weight plate
4
for the elastic support. Supporting legs
7
made of resin are put between damper
6
and circuit board
3
. Supporting pins
5
are crashed at the tips toward the circuit board
3
side after penetrating dampers
6
, supporting legs
7
and circuit board
3
. Thus, circuit board
3
and weight plate
4
are elastically supported and fixed. A metallic supporting pin
8
is inserted and fixed vertically to weight plate
4
, on the circuit board
3
side, as shown in FIG.
19
. One end of a metallic, supporting pin
9
, is inserted, is fixed to supporting pin
8
, and is parallel to weight plate
4
. The diameter of supporting pin
9
is about one fifth of the diameter of supporting pin
8
. Furthermore supporting pin
9
is made of metallic material having elasticity such as a piano wire, wherein the other end of supporting pin
9
fixed by soldering to a metal plate
10
.
One end of each metallic driver plates
11
and
12
, facing other across supporting pins
8
and
9
, is fixed to each side of metal plate
10
. Plate-shaped piezoelectric elements
11
a
and
12
a
are fixed on the surfaces of metallic driver plates
11
and
12
, respectively. In this way, the tuning fork type driving part is formed. The other ends of driver plates
11
and
12
are twisted orthogonally so that piezoelectric elements
11
a
and
12
a
and other plate-shaped piezoelectric elements
13
a
and
14
a
are fixed on detector plates
13
and
14
, as shown in FIG.
19
. In this way, the detector part is formed. A sensor element is composed of the driver part and the detector part.
There is a problem of a usual angular velocity sensor however. Namely, the usual sensor has no ability to judge detected information, drawn to a malfunction of the components, as such, nor the ability to send such information, judged to be a malfunction of the components, to the outside.
The present invention aims to be able to detect, from the outside, the state in which the sensor can not perform a correct detection resulting from partial damage, thereby providing a highly reliable angular velocity sensor.
SUMMARY OF THE INVENTION
To achieve the purpose, an angular velocity sensor of the present invention includes drive means including a sensor element having a driver part and a detector part for detecting an angular velocity, a driver circuit for supplying a driving signal to the driving part of the sensor element and a monitor circuit to which a monitor signal is supplied from the sensor element and stably driving and vibrating the driver part of the sensor element by applying the output of the monitor circuit to the driver circuit through an AGC (automatic gain control) circuit, detection means including a charging amplifier to which an output of the detector part of the sensor element is supplied and a synchronous detector to which an output of the charging amplifier is supplied through a band pass filter and detecting an output of the band pass filter synchronizing with a driving signal from the drive means and outputting an angular velocity signal, and self diagnosis means receiving a mechanical coupling signal obtained from the detection means other than an angular velocity signal detecting abnormality of the sensor element and outputting a self diagnosis signal.
According to the above composition, by making the mechanical coupling signal always obtained from the detection, means a signal for self diagnosis because of its composition, whether the angular velocity signal is in a state which can perform a normal detection can be detected or not and because the mechanical coupling signal surely generates, it is unnecessary to independently provide means for generating the mechanical coupling signal arid not only the composition is very simple and can be highly reliable for self diagnosis but also it is possible to know the timing which the characteristic becomes stable after the sensor start to work and to utilize an sensor output more early.


REFERENCES:
patent: 4671112 (1987-06-01), Kimura et al.
patent: 5131273 (1992-07-01), Tabata et al.
patent: 5293779 (1994-03-01), Nakamura et al.
patent: 5447066 (1995-09-01), Terada et al.
patent: 3-226620 (1991-10-01), None
patent: 4-215017 (1992-05-01), None
patent: 6-18267 (1994-01-01), None
patent: 7-181042 (1995-07-01), None

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