Measuring and testing – Speed – velocity – or acceleration – Angular rate using gyroscopic or coriolis effect
Reexamination Certificate
2003-06-04
2004-10-05
Chapman, John E. (Department: 2856)
Measuring and testing
Speed, velocity, or acceleration
Angular rate using gyroscopic or coriolis effect
C331S156000, C310S370000
Reexamination Certificate
active
06799461
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tuning fork vibrator for use in a device for correcting an error caused by hand movements or vibrations that occur during operation of a video camera, for example, a vibrating gyroscope including the vibrator, an electronic apparatus including the vibrator, and a method of manufacturing the tuning fork vibrator.
2. Description of the Related Art
Examples of conventional tuning fork vibrators are disclosed in Patent Document 1 (referred to below as Conventional Example 1) and Patent Document 2 (referred to below as Conventional Example 2).
In the tuning fork vibrator of the Conventional Example 1, as shown in
FIG. 22
, a tuning fork vibrator
1
includes a long plate-shaped piezoelectric member
2
, in which a slit
3
is formed to extend from the first principal surface thereof to the second principal surface by cutting the piezoelectric member
2
from one end thereof so as to form two legs
4
and
5
.
A tuning fork vibrator in the Conventional Example 2, as shown in
FIG. 1
of Patent Document 2, includes two piezoelectric columnar vibrators arranged such that an end of each of the vibrators is fixed to a base.
The description of driving methods of conventional tuning fork vibrators is omitted.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 8-128830
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2000-193458
It is difficult to manufacture the tuning fork vibrator according to the Conventional Example 1 by cutting a piezoelectric member from the first principal surface or the second principal surface using a dicing saw to form a slit between two legs. As shown in
FIG. 23
, a block
6
is made by bonding a plurality of piezoelectric members prior to forming slits in the thickness direction and the width direction, slits
3
are formed on the block
6
using a wire saw or a dicing saw, and the piezoelectric members
2
that are bonded together are separated.
However, this method complicates the manufacturing process by requiring initial bonding of the piezoelectric members which must be followed by the step of separating them. If an electrode is formed on the first principal surface or the second principal surface of the tuning fork vibrator, the electrode must be formed for each separated tuning fork vibrator, which further complicates the manufacturing process. If the electrodes are formed on a mother substrate prior to forming slits, the electrode-forming process must be performed prior to the slit-forming process, such that the positional accuracy of the electrodes on a leg portion deteriorates.
On the other hand, since in the tuning fork vibrator according to the Conventional Example 2, each vibrator is columnar-shaped, each vibrator is easily separated from a mother substrate using a dicing saw. Electrodes formed in advance on a front surface of the mother substrate, on which grooves are made by a dicing saw, can be separated prior to separating each vibrator with the same dicing saw. Since the separation of the electrodes and the separation of the vibrators are performed in a single process, the problems of Conventional Example 1 are eliminated.
However, in the Conventional Example 2, because the vibrator is not integral with a base, the number of parts increases which complicates the manufacturing process. In addition, when two vibrators are fixed to one base, positional displacement and unbalanced fixing strength make it difficult to achieve a well-balanced tuning fork vibrator.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, preferred embodiments of the present invention provide a well-balanced tuning fork vibrator, a vibrating gyroscope including the tuning fork vibrator, an electronic apparatus including the tuning fork vibrator, and a method of manufacturing the tuning fork vibrator.
A tuning fork vibrator according to a preferred embodiment of the present invention includes a long plate-shaped vibration unit having a first principal surface and a second principal surface, a base disposed at one end of the second principal surface of the vibration unit in the longitudinal direction, wherein at least one slit for dividing the vibration unit into at least two legs along the longitudinal direction symmetrically in the width direction of the vibration unit is provided in the vibration unit, and the slit includes a portion of the base that is in the vicinity of the vibration unit.
In the tuning fork vibrator, the vibration unit is preferably divided into at least three legs by the slits, and further includes a support pin fixed to the leg in the vicinity of the center of the second principal surface. The support pin supports the vibration unit and the base in midair.
The base preferably has a substantially U-shaped configuration including three straight line-segments which surround the vibration unit on three sides, which are provided on one end side in the longitudinal direction and on both sides in the width direction. Alternatively, the base may have a substantially rectangular frame-shape which surrounds the vibration unit on four sides.
In the tuning fork vibrator according to preferred embodiments of the present invention, the base is preferably integrated at least with the second principal surface of the vibration unit. Alternatively, the base may be provided separately from the vibration unit, and bonded to the vibration unit.
Furthermore, the vibration unit may have a bimorph structure including bonded piezoelectric members which are polarized in opposite directions to each other in a direction of the thickness between the first principal surface and the second principal surface of the vibration unit, a unimorph structure including a piezoelectric member polarized in the thickness direction and a non-piezoelectric material which are bonded together, or a structure including a non-piezoelectric material, in which a piezoelectric element which is polarized in the thickness direction of the vibration unit is provided on one principal surface of the non-piezoelectric material.
A vibrating gyroscope according to another preferred embodiment of the present invention includes the tuning fork vibrator described above.
A vibrating gyroscope according to various preferred embodiments of the present invention includes a tuning fork vibrator having two long legs formed by bonding piezoelectric members polarized in opposite directions to each other in a direction of the thickness between a first principal surface and a second principal surface, so as to have a tuning fork shape with one end thereof fixed, wherein two electrodes divided in the width direction are provided on the first principal surface of the respective two legs while an electrode is provided on the second principal surface, wherein among the four electrodes provided on the first principal surface of the respective two legs, two electrodes arranged inside-to-inside or outside-to-outside are connected together to define a driving electrode and the remaining two electrodes define a detection electrode which also defines as a feedback electrode, and the electrodes provided on the second principal surfaces of the two legs are further connected together and are connected to a reference voltage or are floating. This tuning fork vibrator preferably has a bimorph structure described above.
Also, a vibrating gyroscope according to preferred embodiments of the present invention includes a tuning fork vibrator having two long legs formed by bonding a piezoelectric member, being polarized in the thickness direction and having two electrodes divided in the width direction on a first principal surface and an electrode on a second principal surface, to a non-piezoelectric element, so as to have the first principal surface and the second principal surface, respectively, and arranged in a tuning fork shape with one end thereof fixed, wherein among the four electrodes provided on the first principal surface of the respective two legs, two electrodes which
Fujimoto Katsumi
Yamamoto Hironari
Chapman John E.
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
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