Electrostatic actuator

Details Electrostatic actuator Electrostatic actuator

2001-10-05

2003-03-11

Jamai, Karl (Department: 2834)

Electrical generator or motor structure

Non-dynamoelectric

Charge accumulating

C396S075000, C396S133000, C348S374000, C310S012060, C359S823000

Reexamination Certificate

active

06531804

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrostatic actuator.
2. Description of the Related Art
An electrostatic actuator is a kind of an actuator for driving a movable section by an electrostatic force. The basic construction of the electrostatic actuator is disclosed in, for example, Japanese Patent Disclosure (Kokai) No. 8-140367. The electrostatic actuator, which is small and lightweight, can be mounted to, for example, an endoscope, a movable telephone such as a portable telephone, and various PDA (Personal Digital Assistant) for the focusing of the lens system. Such being the situation, the electrostatic actuator attracts keen attentions in recent years.
FIG. 1
is an oblique view showing in a dismantled fashion a conventional electrostatic actuator
100
. As shown in
FIG. 1
, the electrostatic actuator
100
comprises stators
101
A,
101
B each being in the shape of a flat plate, a movable section
102
made of an electrical conductor and substantially in the form of a parallelepiped, and spacers
103
A,
103
B each being substantially in the form of a parallelepiped.
The stators
101
A,
101
B are bonded to the spacers
103
A,
103
B, respectively, in parallel and apart from each other. The movable section
102
is inserted into the space defined by the stators
101
A,
101
B and the spacers
103
A,
103
B such that a gap is provided between the movable section
102
and each of the stators
101
A,
101
B and the spacers
103
A,
103
B. It should be noted that the movable section
102
is movable along an imaginary axis A equidistant from the stators
101
A,
101
B and also equidistant from the axis in the longitudinal direction of each of the spacers
103
A and
103
B.
Oblong stator electrodes
104
A,
104
B and
105
A,
105
B are formed by patterning on the mutually facing surfaces of the stators
101
A and
101
B, respectively. The stator electrodes
104
A,
104
B,
105
A and
105
B are substantially equal to each other in the area. As apparent from the drawing, the stator electrode
104
A and the stator electrode
105
A are positioned to face each other. Likewise, the stator electrode
104
B and the stator electrode
105
B are positioned to face each other. Also, the stator electrodes
104
A and
104
B are arranged along the imaginary axis A and formed apart from each other on both sides of the stator
101
A. Likewise, the stator electrodes
105
A and
105
B are arranged like the stator electrodes
104
A and
104
B and are shaped equal to the stator electrodes
104
A and
104
B. It should be noted that the gap between the movable section
102
and each of the stators
101
A and
101
B is set at about several microns.
If voltage of a predetermined pattern is applied to the stator electrodes
104
A,
104
B,
105
A and
105
B, the movable section
102
is moved between the stators
101
A and
101
B so as to be moved microscopically along the imaginary axis A.
The procedure for moving the movable section
102
will now be described with reference to
FIGS. 2
to
4
E.
FIG. 2
is a sideward cross sectional view schematically showing the construction of the actuator shown in FIG.
1
.
FIG. 3A
is a waveform diagram showing the voltage pattern of the voltage applied to the stator electrode
105
B.
FIG. 3B
is a waveform diagram showing the voltage pattern of the voltage applied to the stator electrode
105
A.
FIG. 3C
is a waveform diagram showing the voltage pattern of the voltage applied to the stator electrode
104
B. Further,
FIG. 3D
is a waveform diagram showing the voltage pattern of the voltage applied to the stator electrode
104
A.
(1) In the first step, voltage V [V] is applied to the stator electrodes
104
A,
104
B during the time period between time points t
0
and t
1
, as shown in
FIGS. 3C and 3D
. As a result, the movable section
102
is temporarily attracted to and held by the stator electrodes
104
A,
104
B by the electrostatic force generated between the stator electrodes
104
A and
104
B, as shown in FIG.
4
A.
(2) In the next step, voltage V [V] is applied to the stator electrode
105
B, with voltage V [V] kept applied to the stator electrode
104
A, during the time period between time points t
1
and t
2
, as shown in
FIGS. 3A and 3D
. As a result, one end of the movable section
102
is held by the stator electrode
104
A and the movable section
102
is swung about the particular one end in the clockwise direction, as shown in FIG.
4
B. In other words, if voltage is applied to the stator electrode
105
B with one end of the movable section
102
held by the stator electrode
104
A, the other end of the movable section
102
is electrostatically attracted by the stator electrode
105
B so as to be held temporarily. It should be noted that the other end of the movable section
102
is slightly moved by a distance &dgr; to the left in
FIGS. 4A and 4B
, compared with the state (1) shown in FIG.
4
A.
(3) Then, voltage V [V] is applied to the stator electrode
105
A, with voltage V [V] kept applied to the stator electrode
105
B, during the time period between time points t
2
and t
3
, as shown in
FIGS. 3A and 3B
. As a result, the other end of the movable section
102
is held by the stator electrode
105
B, and the movable section
102
is swung about the other end of the movable section
102
in the counterclockwise direction. It follows that the movable section
102
is temporarily held by the stator electrodes
105
A and
105
B, as shown in FIG.
4
C. In other words, since voltage is applied to the stator electrode
105
A, with the other end of the movable section
2
held by the stator electrode
105
B, one end of the movable section
102
is electrostatically attracted to and held temporarily by the stator electrode
105
A. In this case, the movable section
102
is slightly moved to the left in
FIG. 4C
by a distance 2&dgr;, compared with the state shown in FIG.
4
A.
(4) Further, voltage V [V] is applied to the stator electrode
104
B, with voltage V [V] kept applied to the stator electrode
105
B, during the time period between time points t
3
and t
4
, as shown in
FIGS. 3B and 3C
. As a result, one end of the movable section
102
is held by the stator electrode
105
A, and the movable section
102
is swung about said one end in the counterclockwise direction, as shown in FIG.
4
D. In other words, since voltage is applied to the stator electrode
104
B, with one end of the movable section
102
held by stator electrode
105
A, the other end of the movable section
102
is electrostatically attracted to and temporarily held by the stator electrode
104
B. In this case, the other end of the movable section
102
is slightly moved to the left in
FIG. 4D
by a distance 2 &dgr;, compared with the state shown in FIG.
4
A.
(5) Still further, voltage V [V] is applied to the stator electrode
104
A, with voltage V [V] kept applied to the stator electrode
104
B during the time period between time points t
4
and t
5
, as shown in
FIGS. 3C and 3D
. As a result, the other end of the movable section
102
is held by the stator electrode
104
B, and the movable section
102
is swung about the other end in the clockwise direction. It follows that the movable section
102
is held temporarily by the stator electrodes
104
A and
104
B. In other words, since voltage is applied to the stator electrode
104
A, with the other end of the movable section
102
kept held by the stator electrode
104
B, one end of the movable section
102
is electrostatically attracted to and held temporarily by the stator electrode
104
A. In this case, the movable section
102
is slightly moved to the left in
FIG. 4E
by a distance 2&dgr;, compared with the state shown in FIG.
4
A.
As described above, it is possible to move the movable section
102
to the left by a desired distance by repeatedly applying the operations described above to the movable section
102
.
Incidentally, it is possible to move the movab

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