Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2001-02-22
2004-11-23
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S366000, C310S316010, C310S352000
Reexamination Certificate
active
06822375
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibrating gyroscope and an electronic device using the same, and more specifically, it relates to a vibrating gyroscope for use in video cameras having an anti-camera-shake function, car navigating systems, pointing devices, and the like, and an electronic device using the same.
2. Description of the Related Art
FIG. 11
is a perspective view of a vibrating gyroscope comprising a vibrator
50
, and
FIGS. 12A-12C
show a plan view, a front view, and a bottom view, respectively, thereof. The vibrating gyroscope shown in FIGS.
11
and
12
A-
12
C is disclosed in Japanese Unexamined Patent Application Publication No. 11-125526.
In
FIG. 11
, the vibrator
50
includes a first piezoelectric substrate
101
having one principal plane on which a first strip electrode is formed on the top surface and which is polarized in the thickness direction; and a second piezoelectric substrate
102
having one principal plane on which a second strip electrode is formed on its bottom surface and which is polarized in the thickness direction. The other principal plane of the first piezoelectric substrate
101
and the other principal plane of the second piezoelectric substrate
102
are bonded via an intermediate electrode
103
.
The first strip electrode has a dividing slot S
0
extending in the longitudinal direction thereof, and dividing slots S
1
and S
2
that are formed widthwise of the first strip electrode to be slightly closer in the longitudinal direction to the center than the positions to which nodes N
1
and N
2
are vertically projected on the first strip electrode. Hence, the first strip electrode is divided into electrode parts
104
and
105
by the dividing slot S
0
, and the electrode parts
104
and
105
are further divided into the electrode parts
104
a
,
104
b
,
104
c
,
105
a
,
105
b
, and
105
c
by the dividing slots S
1
and S
2
. The second strip electrode is composed of an electrode part
106
a.
Supporting members
107
a
and
107
b
which also function as leads are disposed at positions to which the nodes N
1
and N
2
of the vibrator
50
are projected on the first strip electrode; and supporting members
507
c
and
507
d
which also function as leads are disposed at positions to which the nodes N
1
and N
2
are projected on the second strip electrode. A technique such as soldering is used to connect the supporting member
107
a
to the electrode parts
105
a
,
104
b
, and
105
b
; the supporting member
107
b
to the electrode parts
104
a
,
104
c
, and
105
c
; and the supporting members
507
c
and
105
d
to the electrode part
106
a
. The supporting members
107
a
,
107
b
,
507
c
, and
507
d
are made of the same material, are configured in the same form, and have the same rigidity.
By fixing the ends of the supporting members
107
a
,
107
b
,
507
c
, and
507
d
, and by applying drive signals to the electrode part
106
a
serving as a drive electrode via the supporting members
507
c
and
507
d
, the vibrator
50
having such a structure undergoes flexural vibration in the thickness direction with free longitudinal ends, where the nodes for the lowest order mode are the nodes N
1
and N
2
. Since the first piezoelectric substrate
101
and the second piezoelectric substrate
102
are held by the supporting members
107
a
,
107
b
,
507
c
, and
507
d
having the same rigidity, the nodes N
1
and N
2
are formed substantially at the middle between the first strip electrode and the second strip electrode in the thickness direction.
The conventional vibrating gyroscopes have a problem in that there exists a deviation in the vibrating characteristic of the vibrator between respective vibrating gyroscopes produced by the same production method. In addition, the vibrating characteristic of each vibrating gyroscope shifts differently in response to the change in the ambient temperature and over time.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to reduce the deviation in the vibrating characteristic of the vibrator between respective vibrating gyroscopes and realize a vibrating gyroscope which can detect an angular velocity precisely.
The foregoing and other objects are achieved in accordance with certain features of the invention by a vibrating gyroscope which comprises a vibrator having a longitudinal direction and being capable of vibrating in a bending mode in a bending direction perpendicular to the longitudinal direction. The vibrator has first and second nodes which elongate in a direction perpendicular to both the bending direction and the longitudinal direction and first, second, third and fourth supporting member connected to the vibrator such that the first node is interposed between the first and second supporting members and the second node is interposed between the third and fourth supporting members. The first node is located at the vicinity of either the first supporting member or the second supporting member, and the second supporting member is located at the vicinity of either third supporting member or the fourth supporting member.
It is preferable that the first supporting member and the second supporting member have the different rigidities, and the third supporting member and fourth supporting member have the different rigidities. To this end, the first supporting member and the second supporting member may have different shapes from each other or have different cross sections from each other. The first supporting member and the second supporting member may also be made of different materials.
According to a vibrator of the present invention, supporting members having different rigidities are located at positions to which nodes are projected on a first strip electrode and a second strip electrode. Hence, the nodes are displaced toward either the first strip electrode or the second strip electrode with respect to the thickness direction. Therefore, there is less variation in the nodes of the vibrator with respect to the thickness direction, and there is less variation in the driving balance of the vibrator, thus providing an accurate determination of angular velocity.
A vibrating gyroscope according to the present invention is less affected by disturbances or changes over time because the driving balance of a vibrator is maintained for stable vibration, thus providing an accurate determination of angular velocity.
An electronic device according to the present invention incorporates a vibrating gyroscope capable of accurately determining an angular velocity, thus forming a precise control mechanism.
For the purpose of illustrating the invention, there is shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
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Mori Akira
Toyoshima Isao
Gonzalez Julio
Keating & Bennett LLP
Mullins Burton S.
Murata Manufacturing Co. Ltd.
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