Measuring and testing – Speed – velocity – or acceleration – Response to multiple sensing means or motion conditions
Reexamination Certificate
2000-10-23
2004-04-20
Williams, Hezron (Department: 2856)
Measuring and testing
Speed, velocity, or acceleration
Response to multiple sensing means or motion conditions
C073S504030
Reexamination Certificate
active
06722198
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to external-force detecting sensors capable of detecting angular velocity and acceleration.
2. Description of the Related Art
FIG. 3
shows the top view of a structural example of a conventional sensor unit
2
constituting a gyroscope
1
. The sensor unit
2
has a substrate
3
. On the upper surface of the substrate
3
, a supporting/fixing portion
4
, comb-teeth-formed driving fixed-electrode portions
5
(
5
a
,
5
b
,
5
c
,
5
d
,
5
e
,
5
f
,
5
g
, and
5
h
), and detecting fixed-electrode portions
6
(
6
a
,
6
b
,
6
c
,
6
d
,
6
e
, and
6
f
) are disposed in a fixing manner. The supporting/fixing portion
4
is connected to an oscillating element
8
via supporting portions
7
(
7
a
and
7
b
).
The oscillating element
8
is spaced from the top surface of the substrate
3
and can oscillate in two directions including an X direction and a Y direction shown in FIG.
3
. The oscillating element
8
is constituted of drive beams
9
(
9
a
,
9
b
,
9
c
, and
9
d
), an outer frame
10
, comb-teeth-formed driving movable-electrode portions
11
(
11
a
,
11
b
,
11
c
,
11
d
,
11
e
,
11
f
,
11
g
, and
11
h
), supporting portions
12
(
12
a
and
12
b
), detecting beams
13
(
13
a
,
13
b
,
13
c
, and
13
d
),an inner frame
14
, and comb-teeth-formed detecting movable-electrode portions
15
(
15
a
,
15
b
,
15
c
,
15
d
,
15
e,
and
15
f
).
That is, one end of the drive beam
9
a
and one end of the drive beam
9
b
are commonly connected to the supporting portion
7
a
. One end of the drive beam
9
c
and one end of the drive beam
9
d
are commonly connected to the supporting portion
7
b
.
The remaining ends of the drive beams
9
a
,
9
b
,
9
c
, and
9
d
are commonly connected to the outer frame
10
.
Regarding the outer frame
10
, comb-teeth-formed driving movable-electrode portions
11
are disposed in such a manner that they mesh with the corresponding comb-teeth-formed driving fixed-electrode portions
5
via distances therebetween. The pairs of the comb-teeth-formed driving fixed-electrode portions
5
a
,
5
b
,
5
c
, and
5
d
and the comb-teeth-formed driving movable electrode portions
11
a
,
11
b
,
11
c
, and
11
d
, which are mutually opposing, form a first driving section, and the pairs of the comb-teeth-formed driving fixed-electrode portions
5
e
,
5
f
,
5
g
, and
5
h
and the comb-teeth-formed driving movable-electrode portions
11
e
,
11
f
,
11
g
, and
11
h
form a second driving section.
In addition, regarding the outer frame
10
, the supporting portions
12
a
and
12
b
are formed in an extended manner toward the inner side of the outer frame
10
. The detecting beams
13
a
and
13
b
are extended from the top-end side of the supporting portion
12
a
, and the detecting beams
13
c
and
13
d
are extended from the supporting portion
12
b.
The inner frame
14
is commonly connected to the extended top-end sides of the detecting beams
13
a
,
13
b
,
13
c
, and
13
d.
Regarding the inner frame
14
, the comb-teeth-formed detecting movable-electrode portions
15
are disposed in such a manner that they mesh with the corresponding comb-teeth-formed detecting fixed-electrode portions
6
via distances therebetween. The pairs of the comb-teeth-formed detecting fixed-electrode portions
6
a
,
6
b
, and
6
c
and the comb-teeth-formed detecting movable-electrode portions
15
a
,
15
b
, and
15
c
, which are mutually opposing, form a first detecting section, and the pairs of the comb-teeth-formed detecting fixed-electrode portions
6
d
,
6
e
, and
6
f
and the comb-teeth-formed detecting movable-electrode portions
15
d
,
15
e
, and
15
f
, which are mutually opposing, form a second detecting section.
A conductive pattern for supplying electrical power from the outside to the driving fixed-electrode portions
5
and a conductive pattern electrically connected to the detecting fixed-electrode portions
6
are formed. However, this is not shown in the figure.
In the sensor unit
2
, when an AC driving voltage (a driving signal) is applied between the driving fixed-electrode portions
5
and the driving movable-electrode portions
11
, which are mutually opposing, according to changes in the magnitude of electrostatic power based on the driving voltage, the entire oscillating element
8
oscillates in the X direction shown in
FIG. 3
by using the flexibility of the drive beams
9
, with the supporting portions
7
a
and
7
b
serving as fulcrums.
In the state in which the oscillating element
8
oscillates in the X direction, when the oscillating element
8
rotates around a Z direction as a center axis (which is a direction perpendicular to the paper surface in FIG.
3
), a Coriolis force occurs in a direction orthogonal both to the driving direction (X direction) ofthe oscillating element
8
and the central-axis direction (Z direction) of rotation, that is, in a Y direction. By the Coriolis force occurring in the Y direction, the inner frame
14
ofthe oscillating element
8
performs detection/oscillation in the Y direction relatively with respect to the outer frame
10
by using the flexibility of the detecting beams
13
with the supporting portions
12
a
and
12
b
as fulcrums.
The magnitude of angular velocity around the Z axis can be detected by detecting changes in capacitance between the detecting fixed-electrode portions
6
and the detecting movable-electrode portions
15
based on the detection oscillation in the Y direction.
The sensor unit
2
, in order to avoid negative influences such as air damping, for example, is contained in a containing space formed of a glass member to be sealed therein in a reduced-pressure state. In this case, the driving fixed-electrode portions
5
and the detecting fixed-electrode portions
6
of the sensor unit
2
can be electrically connected to the outside via through-holes disposed in the glass member.
In
FIG. 6
, an example of a signal processing circuit connected to the sensor unit
2
is shown with the main part of the sensor unit
2
. A signal processing circuit
20
is constituted of. a first detecting C-V conversion unit
21
, a second detecting C-V conversion unit
22
, a summing amplifier
23
, a differential amplifier
24
, an AGC (Auto Gain Control) unit
25
, a phase inverter
26
, and a synchronous detector
27
. In the illustration shown in
FIG. 6
, in order to describe the structure of the signal processing circuit so as to facilitate understanding, the driving fixed-electrode portions
5
, the detecting fixed-electrode portions
6
, and the oscillating element
8
included in the sensor unit
2
are shown in a simplified manner.
The first detecting C-V conversion unit
21
converts the overall capacitance between the detecting fixed-electrode portions
6
(
6
a
,
6
b
, and
6
c
) and the detecting movable-electrode portions
15
(
15
a
,
15
b
, and
15
c
) forming the first detecting section of the sensor unit
2
into a voltage to output as a signal. In addition, the second detecting C-V conversion unit
22
converts the overall capacitance between the detecting fixed-electrode portions
6
(
6
d
,
6
e
, and
6
f
) and the detecting movable-electrode portions
15
(
15
d
,
15
e
, and
15
f
) forming the second detecting section into a voltage to output as a signal.
When the oscillating element
8
oscillates only in the X direction, the signal output from the first detecting C-V conversion unit
21
, for example, is a signal A
1
having a waveform as indicated by a dot-dash line A
1
shown in FIG.
4
A. The signal A
1
produced due to the oscillation of the oscillating element
8
is 90° out of phase with the driving signal applied between the driving fixed-electrode portions
5
and the driving movable-electrode portions
11
to allow the oscillating element
8
to oscillate.
In addition, when the inner frame
14
of the oscillating element
8
oscillates not only in the X direction but also in the Y direction due to angular velocity, the output signal of the f
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
Saint-Surin Jacques
Williams Hezron
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