Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2001-12-12
2003-07-15
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C264S436000
Reexamination Certificate
active
06593681
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to polarization of a coaxial flexible piezoelectric cable.
2. Related Arts
Generally, as shown in
FIG. 5
, a coaxial flexible piezoelectric cable comprises a piezoelectric body tube
3
comprising a coaxial flexible piezoelectric body
2
formed surrounding a core electrode
1
, an outer electrode
4
formed on the outer surface of the piezoelectric body tube
3
, and a protective coat layer (not shown) formed surrounding the outer electrode
4
.
Hitherto, the flexible piezoelectric body cable is polarized as follows:
Document 1 (“Atuden ceramic funmatu to gouseigomu tokaranaru atudenfukugouzairyou,” Funntai to kougyou, 22kan, 1gou, 50-56 pp) shows that a high voltage is applied between the core electrode
1
and the outer electrode
4
for polarizing the coaxial flexible composite piezoelectric body
2
. This is also disclosed in U.S. Pat. No. 4,568,851. Since the directions of spontaneous polarization of ceramic particles are made identical with the electric field direction by polarization, piezoelectricity is given to the coaxial flexible composite piezoelectric body
2
. In this point, the polarization bears an important role.
Further, a coaxial flexible piezoelectric cable comprises a piezoelectric body tube
203
comprising a coaxial flexible piezoelectric body
202
formed surrounding a core electrode
201
, an outer electrode
204
formed on the outer surface of the piezoelectric body tube
203
, and a protective coat layer
205
formed surrounding the outer electrode
204
, as shown in FIG.
9
.
In the method, when a high voltage is applied between the core electrode
401
and the outer electrode
404
, if the coaxial flexible piezoelectric body
402
contains a defect such as a minute crack or gap, discharge occurs in the defective part, and the core electrode
401
and the outer electrode
404
are electrically short-circuited. Consequently, it is made impossible to apply a high voltage between the core electrode
401
and the outer electrode
404
and thus it is made impossible to polarize the coaxial flexible piezoelectric body
402
(usually, having a length of several hundred meters or more). Since the presence of a defect cannot be detected until a high voltage is applied between the core electrode
401
and the outer electrode
404
, in other words, until completion as a coaxial flexible piezoelectric body cable except for polarizing, manufacturing becomes unstable and yield is reduced.
Thus, the following polarization method of the flexible piezoelectric body cable is possible:
As shown in
FIG. 17
, a polarization apparatus is possible wherein a piezoelectric body tube
403
comprising a coaxial flexible piezoelectric body
402
formed surrounding a core electrode
401
is disposed on a block-like conductor
406
and DC voltage generation means
409
is connected to the block-like conductor
406
and the core electrode
401
through leads
408
and
481
for applying a DC voltage. According to the polarization apparatus, the coaxial flexible piezoelectric body
402
is disposed on the block-like conductor
406
and thus the block-like conductor
406
acts as an outer electrode
404
. Therefore, a DC voltage can be applied between the block-like conductor
406
and the core electrode
401
by the DC voltage generation means
409
for polarizing the coaxial flexible piezoelectric body
402
of the portion disposed on the block-like conductor
406
.
[Problems to be Solved]
However, when a high voltage is applied between the core electrode
1
and the outer electrode
4
, if the coaxial flexible composite piezoelectric body
2
contains a defect such as a minute crack or gap, minute discharge occurs in the defective part. This minute discharge causes the conductive material forming the core electrode
1
and the outer electrode
4
and the material forming the coaxial flexible composite piezoelectric body
2
to be thermally evaporated and scattered, short-circuiting the core electrode
1
and the outer electrode
4
. Consequently, it is made impossible to apply a high voltage between the core electrode
1
and the outer electrode
4
and thus it is made impossible to polarize the coaxial flexible composite piezoelectric body
2
(usually, having a length of several hundred meters or more); this is a problem.
Since the presence of a defect cannot be detected until a high voltage is applied between the core electrode
1
and the outer electrode
4
, in other words, until completion as a coaxial flexible piezoelectric cable except for polarizing, manufacturing becomes unstable and yield is reduced; this is also a problem.
Further, the method in the related art involves the following problems: When a high voltage is applied between the core electrode
201
and the outer electrode
204
, if the coaxial flexible piezoelectric body
202
contains a defect such as a minute crack or gap, minute discharge occurs in the defective part. This minute discharge causes the material forming the flexible piezoelectric body
202
to be thermally evaporated and scattered, short-circuiting the core electrode
201
and the outer electrode
204
. Consequently, it is made impossible to apply a high voltage between the core electrode
201
and the outer electrode
204
and thus it is made impossible to polarize the coaxial flexible piezoelectric body
202
(usually, having a length of several hundred meters or more).
Since the presence of a defect cannot be detected until a high voltage is applied between the core electrode
201
and the outer electrode
204
, in other words, until completion as a coaxial flexible piezoelectric cable except for polarizing, manufacturing becomes unstable and yield is reduced.
Still further, the method in the related art involves the following problems: When a high voltage is applied between the core electrode
301
and the outer electrode
304
, if the coaxial flexible piezoelectric body
302
contains a defect such as a minute crack or gap, minute discharge occurs in the defective part. This minute discharge causes the material forming the flexible piezoelectric body
302
to be thermally evaporated and scattered, short-circuiting the core electrode
301
and the outer electrode
304
. Consequently, it is made impossible to apply a high voltage between the core electrode
301
and the outer electrode
304
and thus it is made impossible to polarize the coaxial flexible piezoelectric body
302
(usually, having a length of several hundred meters or more).
Since the presence of a defect cannot be detected until a high voltage is applied between the core electrode
301
and the outer electrode
304
, in other words, until completion as a coaxial flexible piezoelectric cable except for polarizing, manufacturing becomes unstable and yield is reduced.
Still further, the method in the related art involves the following problem:
If a DC voltage is applied to the block-like conductor
406
and the core electrode
401
by the DC voltage generation means
409
, a force of causing the coaxial flexible piezoelectric body
402
and the block-like conductor
406
to attract each other is generated by an electrostatic force. Thus, to move the piezoelectric body tube
403
, a frictional force occurs between the coaxial flexible piezoelectric body
402
and the block-like conductor
406
, making it impossible to move the piezoelectric body tube
403
. If the piezoelectric body tube
403
can be moved, a large force is required.
SUMMARY OF THE INVENTION
[Means for Solving the Problems]
To solve the above-described problems, according to the invention, there is provided a polarization apparatus of a coaxial flexible piezoelectric cable, comprising a first conductor drum having a plurality of grooves for coming in contact with a roughly half peripheral surface of a piezoelectric body tube comprising a coaxial flexible piezoelectric body formed surrounding a core electrode and being rotated in a given direction, a second conductor drum being placed behind the first conductor drum and
Ebisawa Mitsuo
Fujii Yuko
Ito Masahiko
Kanazawa Narutoshi
Nagai Takeshi
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