Acceleration detection type gyro device

Details Acceleration detection type gyro device Acceleration detection type gyro device

2003-01-02

2003-12-30

Moller, Richard A. (Department: 2856)

Measuring and testing

Speed, velocity, or acceleration

Angular rate using gyroscopic or coriolis effect

Reexamination Certificate

active

06668648

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an acceleration-detecting type gyro apparatus, which is suitable for use in mobile objects such as automobiles, ships, or airplanes, for detecting an angular velocity, or angular change, and acceleration relative to the inertial space. More particularly, the present invention relates to an extremely small acceleration-detecting type gyro apparatus in which a gyro rotor is being supported by electrostatic supporting forces in a floating state.
BACKGROUND ART
Referring to
FIG. 1
to
FIG. 5
, an example of a conventional gyro apparatus will be described. This gyro apparatus has been disclosed in the Japanese published application No. HEI-7 (1995)-125345, filed on May 24, 1995 by the same applicant as the present application. Refer to the above application for the detailed description.
Referring to
FIG. 1
, this gyro apparatus will be described. The gyro apparatus comprises: a thin disk-like gyro rotor
20
; and a gyro case
21
with the gyro rotor
20
housed therein.
XYZ coordinates for the gyro apparatus are set as shown in the figure. The Z axis is set upwardly along the central axis of the gyro apparatus, and the X axis and the Y axis are set perpendicular to the above Z axis. A spin axis of the gyro rotor
20
is disposed along the Z axis.
As shown in
FIG. 1A
, the gyro case
21
comprises: an upper bottom member
22
, a lower bottom member
24
, and a spacer
23
which connects the both, and the spacer
23
has an inner annular wall
23
A. Thus, a disk-like closed cavity
26
in which the gyro rotor
20
is housed is formed within the gyro case
21
with the inner surfaces of the upper bottom member
22
and the lower bottom member
24
, and the inner wall
23
A of the spacer
23
. The cavity
26
has been evacuated by a suitable method.
A concave portion
23
B is formed outside of the inner annular wall
23
A of the spacer
23
, and the concave portion
23
B is connected to the cavity
26
through a passage
23
C. The height of the passage
23
C may be from 2 to 3 micrometers. A getter
33
is disposed in the above concave portion
23
B, whereby it is possible to maintain the cavity
26
at a high degree of vacuum for a long period of time.
The gyro rotor
20
is formed with a conductive material. For example, single crystal silicon may be used as such conductive material. By using the single crystal material, a gyro rotor with less thermal deformation, smaller influence by secular change, and higher accuracy may be provided. The upper bottom member
22
and the lower bottom member
24
of the gyro case
21
are formed with a non-conductive material, for example, with glass. The spacer
23
may be formed with the same material as that of the gyro rotor
20
.
As shown in the right halves of
FIGS. 1A and 1B
, a plurality of annular electrode portions
200
A,
200
B,
200
C,
200
D; and
200
A′,
200
B′,
200
C′,
200
D′ are concentrically formed on the upper surface and the lower surface of the gyro rotor
20
. Specifically, a plurality of annular grooves
200
a,
200
b,
200
c,
200
d;
and
200
a
′,
200
b
′,
200
c
′,
200
d
′ are concentrically formed on the upper and lower surfaces, whereby protruding annular electrode portions are formed.
Driving electrode portions
200
E,
200
E′ are formed at the inner side of the annular electrode portions
200
A,
200
B,
200
C,
200
D; and
200
A′,
200
B′,
200
C′,
200
D′ on the upper and lower surfaces of the gyro rotor
20
. The driving electrode portions
200
E,
200
E′ are formed between two concentric annular grooves
200
d,
200
e;
and
200
d
′,
200
e
′ as a plurality of sectorial protruding portions, and may be annularly disposed in a row along the circumference.
Displacement-detection electrode portions
200
F and
200
F′ are formed in the center portion, that is, at the inner side of the driving electrode portions
200
E and
200
E′ on the upper and lower surfaces of the gyro rotor
20
. Concave portions
200
f,
200
f
′ are formed in the center portion of the above displacement-detection electrode portions
200
F,
200
F′.
The annular electrode portions
200
A,
200
B,
200
C,
200
D and
200
A′,
200
B′,
200
C′,
200
D′; the driving electrode portions
200
E,
200
E′; and the displacement-detection electrode portions
200
F,
200
F′, all of which are formed as a protruding portion on the upper, and lower surfaces of the gyro rotor
20
, may be formed coplanar with each other.
On the other hand, as shown in the left halves of
FIGS. 1A and 1B
, at least three pairs of electrostatic supporting electrodes, in the present example, a first, second, third, and fourth pairs of electrostatic supporting electrodes
221
,
231
,
222
,
232
,
223
,
233
, and,
224
,
234
are disposed on the inner surface of the upper bottom member
22
and the lower bottom member
24
of the gyro case
21
. The four pairs of electrostatic supporting electrodes are spaced with every ninety-degree to each other along the circumferential direction. For example, the first and third pairs of the electrostatic supporting electrodes
221
,
231
, and,
223
,
233
are disposed along the X axis, and the second and fourth pairs of electrostatic supporting electrodes
222
,
232
, and,
224
,
234
are disposed along the Y axis.
Individual electrostatic supporting electrodes comprise a pair of comb-shaped portions. For example, the electrostatic supporting electrode
223
, which is formed on the inner surface of the upper bottom member
22
, in the third pair of electrostatic supporting electrodes
223
,
233
is shown on the left side of FIG.
1
B. This electrostatic supporting electrode
223
includes two comb-shaped portions
223
-
1
,
223
-
2
spaced apart from each other, and the above two comb-shaped portions are spaced apart from each other.
One comb-shaped portion
223
-
1
comprises a radius portion
223
R extending in the radial direction, and a plurality of circumference portions
223
A,
223
C extending in the circumferential direction. Similarly, the other comb-shaped portion
223
-
2
comprises a radius portion
223
R extending in the radial direction, and a plurality of circumference portions
223
B,
223
D extending in the circumferential direction. The circumference portions
223
A,
223
C; and
223
B,
223
D of individual comb-shaped portions
223
-
1
,
223
-
2
are alternately disposed. Terminal portions
223
R′,
223
R′ are formed at the edge of the radius portions
223
R,
223
R of the comb-shaped portions
223
-
1
,
223
-
2
, respectively.
Driving electrodes
225
,
235
are formed on the inner side of four pairs of electrostatic supporting electrodes
221
,
231
,
222
,
232
,
223
,
233
, and,
224
,
234
on the inner surface of the upper bottom member
22
and the lower bottom member
24
of the gyro case
21
, respectively. The above driving electrode
225
,
235
may be configured to be a plurality of sectors which are annularly disposed in a row along the circumference.
Displacement-detection electrodes
226
,
236
are formed in the center portion, that is, on the inner side of the driving electrodes
225
,
235
on the inner surfaces of the upper bottom member
22
and the lower bottom member
24
of the gyro case
21
.
Hereinafter, sizes and relative positions between the annular electrode portions
200
A,
200
B,
200
C,
200
D and
200
A′,
200
B′,
200
C′,
200
D′ of the gyro rotor
20
; and the electrostatic supporting electrodes
221
,
222
,
223
,
224
, and
231
,
232
,
233
,
234
of the upper bottom member
22
and lower bottom member
24
of the gyro case
21
will be described.
With regard to the gyro rotor
20
, the outer diameter D, the thickness t, and the mass may be 5 mm or less, 0.1 mm or less, and 10 milligrams or less, respectively. Four annular electrode portions
200
A,
200
B,
200
C,
200
D; and
200
A′,
200
B′,
200
C′,
200

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