Metal working – Electric condenser making – Solid dielectric type
Reexamination Certificate
2002-09-09
2004-07-27
Arbes, Carl J. (Department: 3729)
Metal working
Electric condenser making
Solid dielectric type
C029S830000, C029S417000, C310S328000, C310S331000
Reexamination Certificate
active
06766568
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piezoelectric/electrostrictive device of a form such that the displacement operation of a piezoelectric/electrostrictive element is transmitted to a pair of right and left movable parts to control a component to be controlled, which component is sandwiched and held by the other ends of the movable parts, or the displacement operation of a pair of right and left movable parts that sandwich and hold a component to be inspected on the other end is sensed by a piezoelectric/electrostrictive element to sense the characteristics of the component to be inspected.
2. Description of the Background Art
Referring to
FIG. 1
, a conventional piezoelectric/electrostrictive device having such a form is constructed in such a manner that a piezoelectric/electrostrictive element
10
b
is disposed on each of the outside surfaces of a pair of right and left movable parts
11
,
12
constituting a base
10
a.
Movable parts
11
,
12
are connected with each other by means of a connecting part
13
on one end thereof, and movable part bodies
11
a
,
12
a
extend towards the other end thereof. The other end of movable part bodies
11
a
,
12
a
are made into mounting parts
11
b
,
12
b
for mounting a component H such as a component to be controlled or a component to be inspected.
Mounting parts
11
b
,
12
b
protrude inwards by a predetermined width from the other end of movable part bodies
11
a
,
12
a
, so as to oppose each other by holding a predetermined interval. Component H is fixed to the inside surfaces (joining surfaces)
11
b
1
,
12
b
1
of mounting parts
11
b
,
12
b
via adhesives h
1
, h
2
on the side surfaces of component H, so as to be sandwiched and held by mounting parts
11
b
,
12
b
of movable parts
11
,
12
.
In a piezoelectric/electrostrictive device having such a form, if component H to be mounted is long in the longitudinal direction of the device, one must increase the length L4 of mounting parts
11
b
,
12
b
, as shown in FIG.
2
. In this case, the total length L1 of the device is elongated by the amount of increase in the length L4 of mounting parts
11
b
,
12
b
. Thus, if the length h of component H to be mounted is equal to the length L4 of mounting parts
11
b
,
12
b
, the total length L1 of the device is restricted by the length h of component H.
On the other hand, in the case of mounting a long component H shown in
FIG. 2
to mounting parts
11
b
,
12
b
, if the length L4 of mounting parts
11
b
,
12
b
are, for example, let as it is shown in
FIG. 1
without being changed, the total length L1 of the device is unchanged irrespective of the length of component H. However, in this case, the length L4 of mounting parts
11
b
,
12
b
will be shorter than the length h of component H, thereby decreasing the area of the joining surface (bonding area) on component H. Therefore, if an ordinary adhesive made of resin is used as adhesives h
1
, h
2
, the adhesive strength on component H decreases. Decrease in the adhesive strength on component H in the worst cases causes component H to be dismounted from mounting parts
11
b
,
12
b.
A component H having a large dimension h in the longitudinal direction will have a mass that is increased by the amount of elongation of the length h if the other dimensions and the density thereof remain unchanged. Therefore, if the bonding area is small, for example, if mounting parts
11
b
,
12
b
are each in a state shown in
FIG. 1
, the impact imposed upon each of the adhesives h
1
, h
2
will be large, whereby component H is more liable to be dismounted from each of mounting parts
11
b
,
12
b.
In a piezoelectric/electrostrictive device having such a form, if component H is dismounted from one of mounting parts
11
b
,
12
b
, the other of mounting parts
11
b
,
12
b
must support component H to succeed receiving the impact applied to component H. In this state, component H is liable to be dismounted from the other mounting part, and also there is a fear that the supporting balance of the mounted state may be lost to cause the one supporting mounting part or the movable part connected thereto to be broken by the action of torsional force.
In order to meet this problem, one must use an adhesive having an extremely high adhesive strength; however, it is generally difficult to obtain a special adhesive that can ensure a sufficient adhesive strength no matter how small the bonding area is. Furthermore, there is naturally a limit even in the case of using an adhesive having such a special property.
In a piezoelectric/electrostrictive device having such a form, in the case of improving the device properties by increasing the displacement of mounting parts
11
b
,
12
b
, one must increase the amount of displacement of the movable part bodies
11
a
,
12
a
by increasing the length of the movable part bodies
11
a
,
12
a
of movable parts
11
,
12
. However, in order to increase the length of the movable part bodies
11
a
,
12
a
of movable parts
11
,
12
without increasing the total length L1 of the device, one must reduce the length of mounting parts
11
b
,
12
b
. As a result of this, the bonding area of joining surfaces
11
b
1
,
12
b
1
at the mounting parts
11
b
,
12
b
will be smaller to weaken the adhesive force of component H to joining surfaces
11
b
1
,
12
b
1
of mounting parts
11
b
,
12
b
all the more, whereby component H will be more liable to be dismounted and drop off from joining surfaces
11
b
1
,
12
b
1
.
In a piezoelectric/electrostrictive device having such a form, in order to mount component H onto mounting parts
11
b
12
b
of movable parts
11
,
12
, component H is bonded to joining surfaces
11
b
1
,
12
b
1
generally through the intermediary of adhesives h
1
, h
2
made of resin. However, adhesives h
1
, h
2
made of resin will have a reduced hardness or reduced Young's modulus when the temperature changes above room temperature. The temperature change of the state of use of piezoelectric/electrostrictive devices is, for example, of a degree within a range from room temperature to 100° C. However, even in this temperature range, adhesives h
1
, h
2
will be softened at a high temperature. For this reason, the distortion of adhesives h
1
, h
2
when an external force is applied will differ greatly between the state of room temperature and the state of higher temperature than this. Therefore, the device properties of the piezoelectric/electrostrictive device having this form will differ greatly at a state of high temperature, even though the device properties in a state of room temperature remain as originally set.
FIGS. 3 and 4
illustrate the operation state of the device at a low temperature such as room temperature and at a higher temperature than room temperature, respectively. The influence caused by such a temperature change (temperature variation) will be larger according as the bonding area is smaller, because the distortion imposed upon the adhesive will be larger according as the bonding area is smaller. Therefore, according as the bonding area increases, the influence of the temperature variation will be smaller.
In a piezoelectric/electrostrictive device having such a form, if component H increases in size to increase its mass, fixing part
13
for fixing the device itself must support the combined mass of component H and the device itself. Therefore, if an impact is received, fixing part
13
is liable to be dismounted. If the length L2 of fixing part
13
is increased in order to increase the bonding area, the total length L1 of the device will also increase.
SUMMARY OF THE INVENTION
Thus, an object of the present invention is to increase the displacement of each movable part and to sufficiently ensure the bonding between each mounting part and the component as well as the fixation of the device itself without changing the total length of the device and without reducing the bonding area at the joining surfaces of the mounting parts in a piezoelectric/electrostrictive device ha
Ikeda Koji
Shibata Kazuyoshi
Takahashi Fumitake
Arbes Carl J.
Burr & Brown
NGK Insulators Ltd.
Nguyen Tai Van
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