Electrical generator or motor structure – Non-dynamoelectric – Charge accumulating
Reexamination Certificate
2001-09-27
2004-01-20
Tamai, Karl (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Charge accumulating
C396S075000, C396S133000, C348S374000, C359S823000, C310S012060
Reexamination Certificate
active
06680558
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrostatic actuator for electrostatically driving a slider or a movable section and a method of driving the same, particularly, to an electrostatic actuator including movable sections that can be driven individually and a method of driving the same.
2. Description of the Related Art
An electrostatic actuator is small and lightweight and, thus, can be used for the focusing of a lens system mounted to an endoscope, a movable telephone such as a portable telephone or an apparatus such as various kinds of PDA (Personal Digital Assistant). Such being the situation, the electrostatic actuator attracts attentions in recent years.
FIG. 1
is an oblique view showing the construction of a conventional electrostatic actuator
100
. As shown in the drawing, the electrostatic actuator
100
comprises a slider or movable section
101
and a stator
102
. The movable section
101
is substantially in the form of a parallelepiped having a through-hole formed therein in a manner to extend in the longitudinal direction of the movable section
101
, and the stator
102
is also substantially in the form of a parallelepiped having a through-hole formed therein in a manner to extend in the longitudinal direction of the stator
102
. The movable section
101
is slidable into the through-hole of the stator
102
such that the movable section
101
is movable within the stator
102
in the longitudinal direction of the stator
102
. Incidentally, a clearance of several microns is provided between the stator
102
and the movable section
101
.
Also, a convex stripe electrodes
103
A and
103
B are formed by, for example, an etching in the movable section
101
so as to form a pair of electrode surfaces facing the inner surfaces of the stator
102
. An optical system of lenses
104
having optical axes extending along the axis of the through-hole are fixed within the through-hole of the movable section
101
. The movable section
101
is moved and the optical system of these lenses is also moved with the movable section
101
so as to adjust the focus of the optical system on a subject to be examined.
A wiring
105
for applying a driving signal to the movable section
101
is connected to the movable section
101
. Glass plates
106
A and
106
B are mounted to those inner surfaces of the stator
102
which face the electrodes
103
A and
103
B, respectively, and first electrodes
107
A of a first group GA and a second group GB and second electrodes
107
B of a third group GC and a fourth group GD are formed on the glass plates
106
A and
106
B, respectively, by patterning a conductive material. The electrodes
107
A of the first group GA and the second group GB are alternately arranged at the same pitch. Likewise, the electrodes
107
B of the third group GC and the fourth group GD are also alternately arranged in the same pitch. Also, the electrodes
107
A and the electrodes
107
B are arranged deviant from each other by a half pitch.
The operation of the electrostatic actuator having the construction described above will now be described with reference to FIG.
2
.
(1) In the first step, a voltage of +V [V] is applied to the first group GA of the electrode
107
A. As a result, an electrostatic attracting force is generated between the electrode
107
A of the first group GA and the electrode
103
A. By this electrostatic attracting force, the movable section
101
begins to be moved toward the glass plate
106
A of the stator
102
, and the electrode
103
A is attracted to the electrode
107
A of the first group GA a predetermined time later.
(2) In the next step, a voltage of +V [V] is applied to the electrode
107
B of the third group GC among the electrodes
107
B, with the result that an electrostatic force is generated between the electrode
107
B of the third group GC and the electrode
103
B. By this electrostatic force, the movable section
101
begins to be moved toward the glass plate
106
B of the stator
102
. As a result, the electrode
103
B is attracted to the electrode
107
B of the third group GC a predetermined time later. The movable section
101
is moved to the right in
FIG. 2
by a distance equal to half the arranging pitch of the electrode
106
A or
106
B, compared with the position described in item (1) above.
(3) Further, a voltage of +V [V] is applied to the second group GB of the electrode
107
A, with the result that an electrostatic force is generated between the electrode
107
A of the second group GB and the electrode
103
A. By this electrostatic force, the movable section
101
begins to be moved again toward the glass plate
106
A, and the electrode
103
A is attracted to the electrode
107
A of the second group GB a predetermined time later. The movable section
101
is moved to the right in
FIG. 2
by a distance equal to the arranging pitch of the electrode
107
A or
107
B, compared with the position described in item (1) above.
(4) Still further, a voltage of +V [V] is applied to the fourth electrode GD of the electrode
107
B, with the result that an electrostatic force is generated between the electrode
107
B of the fourth group GD and the electrode
103
B. By this electrostatic force, the movable section
101
begins to be moved again toward the glass substrate
106
B, and the electrode
103
B is attracted to the electrode
107
B of the fourth group GD. The movable section
101
is moved to the left in
FIG. 2
by a distance equal to 1.5 times as much as the arranging pitch of the electrode
107
A or
107
B, compared with the position described in item (1) above.
The steps of items (1) to (4) described above are repeated so as to move the movable section
101
to the right in
FIG. 2
by a distance equal to half the arranging pitch of the electrodes every time each of the steps of items (2) to (4) is performed.
It should also be noted that, if the voltage is applied to the electrode in the order of items (4), (3), (2) and (1) described above, the movable section
101
can be moved to the right in
FIG. 2
by a distance equal to half the arranging pitch of the electrodes every time each of the steps of items (3) to (1) is performed.
It is possible to move the lens
104
mounted to the movable section
101
by moving the movable section
101
by the steps of items (1) to (4) described above so as to adjust the focus of the lens
104
on the subject.
As described above, in the conventional electrostatic actuator, it is possible to move the movable section to a desired position so as to adjust the focus of the lens on the subject to be photographed. However, the conventional electrostatic actuator gives rise to the problem that it is impossible to realize the zooming function of magnifying or reducing the photographed image. The difficulty is based on the mechanism that the lens system is moved with a single movable section.
It should also be noted that, even if a plurality of movable sections are mounted to the conventional electrostatic actuator for magnifying or reducing the photographed image, it is necessary for the plural movable sections to be moved or fixed independently for magnifying or reducing the photographed image. In the electrostatic actuator of the conventional structure, however, it is impossible to operate the electrostatic actuator with the plural movable sections moved or fixed within the stator independently.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide an electrostatic actuator capable of independently operating movable sections for magnifying or reducing the photographed image.
According to a first aspect of the present invention, there is provided an electrostatic actuator, comprising:
first stator electrodes arranged in a predetermined direction and extending in a direction crossing the predetermined direction;
a second stator electrode arranged to face the first stator electrodes and extending in the predetermined direction;
a third stator electr
Akiba Toshikatsu
Haraguchi Takashi
Kasahara Akihiro
Koga Akihiro
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