Electrical generator or motor structure – Non-dynamoelectric – Charge accumulating
Reexamination Certificate
2001-02-02
2004-06-22
Tamai, Karl (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Charge accumulating
C359S224200, C359S872000, C359S291000
Reexamination Certificate
active
06753638
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of electrostatic actuators and, in particular, to microelectromechanical (MEM) electrostatic actuators.
BACKGROUND
Prior parallel-plate actuators, such as the example illustrated in
FIGS. 1A
(top view),
1
B (side view), and
1
C (side view), are typically designed with gaps
13
that are significantly larger than the stroke range of the actuator. When a voltage is applied between two electrode plates
15
and
10
, an attractive force is produced between the electrode plates that rotates plate
10
. Because the maximum rotation is determined by the separation, or gap
13
, between the two electrode plates
15
and
10
, there must be a large separation in order to obtain a large deflection. The gap
13
needs to be much larger than absolutely necessary for the physical movement of electrode plates
15
and
10
, because if the electrodes approach too closely to each other (e.g., less than about ⅓ of gap
13
), a point of instability is reached where the electrodes
15
and
10
may snap together.
Because the force produced by a parallel-plate actuator is proportional to (voltage/gap)
2
, as gap
13
increases, the voltage must also go up with the square of the distance in order to achieve the same force. With the movement of the structure, electrode plates
15
and
10
do not remain parallel to each other and gap
13
between them decreases. Hence, the voltage required to move electrode plates
15
and
10
a given distance is high, nonlinear, and constantly changing. This may require more complex electronics to control the actuator that may be difficult and costly to build. Also, the use of a large gap may result in cross-talk between adjacent actuators in an array.
Moreover, on the extremely small scale of these actuators, problems are introduced by the need to run conductors for the voltages very close together. With higher voltages, interactions between conductors are hard to avoid and in extreme cases, arcing between conductors will occur, leading to damage to the device. Current parallel plate actuators having a useful range of movement typically require voltages of 300 volts or higher.
U.S. Pat. No. 5,536,988 entitled Compound Stage MEM Actuator Suspended For Multidimensional Motion discloses the use of interlocking comb fingers as X-Y axis actuators for nested stages of MEMs devices. The levitation force produced by comb fingers can also be use to generate torsional actuators. Nevertheless, the primary limitation of comb fingers is on the stroke range. The levitation force produced by comb drives is limited to approximately the same distance that the comb fingers are spaced. This typically makes deflections greater that 5 to 10 microns (&mgr;m) very difficult. Deflections greater than 50 &mgr;m may be needed, however, for mirror actuator applications, which may not be possible to achieve with the comb finger actuators.
SUMMARY OF THE INVENTION
An apparatus and method of actuation are described. For one embodiment, the apparatus may include a stage having a surface and a first blade coupled to the stage with the first blade extending perpendicular to the surface of the stage. The apparatus may also include a frame having a surface and a second blade coupled to the frame. The stage is pivotally coupled to the frame. The second blade extends perpendicular to the surface of the frame and is parallel with the first blade.
For one embodiment the stage may be pivotally coupled to the frame by a torsional flexure. By applying a voltage difference between the first and the second blades, an electrostatically generated torque will cause the stage to rotate to an angle related to the magnitude of the voltage difference.
For another embodiment, the apparatus may include a central stage, a movable frame, and a fixed frame. The central stage may be coupled to the movable frame by a first torsional flexure, and the movable frame may be coupled to the fixed frame by a second torsional flexure, perpendicular to the first. Blade actuators may be attached to the central stage and movable frame to tilt the central stage with respect to the movable stage. Blade actuators may be attached to the movable frame and the fixed frame to tilt the movable stage with respect to the fixed stage. A mirror may be attached to the central stage.
Methods for fabricating a microelectromechanical apparatus are also described. For one embodiment, first trenches are formed in a first side of a substrate. A layer of dielectric material is formed on the first side of the substrate. The first trenches are filled with the dielectric material to provide electrical isolation. A masking layer is patterned on a second side of the substrate that is opposite to the first side of the substrate. Vias are formed on the first side of the substrate. The first side of the substrate is metallized. Second trenches are formed on the first side of the substrate to define structures. The second side of the substrate is deeply etched to form blades. Etching is performed to release the structures.
Additional features and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description that follows.
REFERENCES:
patent: 3493820 (1970-02-01), Rosvold
patent: 4104086 (1978-08-01), Bondur et al.
patent: 4421381 (1983-12-01), Ueda et al.
patent: 4509249 (1985-04-01), Goto et al.
patent: 4519128 (1985-05-01), Chesebro et al.
patent: 4553436 (1985-11-01), Hansson
patent: 4571819 (1986-02-01), Rogers et al.
patent: 4598585 (1986-07-01), Boxenhorn
patent: 4613203 (1986-09-01), Proetel et al.
patent: 4654663 (1987-03-01), Alsenz et al.
patent: 4670092 (1987-06-01), Motamedi
patent: 4688069 (1987-08-01), Joy et al.
patent: 4706374 (1987-11-01), Murakami
patent: 4738500 (1988-04-01), Grupp et al.
patent: 4784720 (1988-11-01), Douglas
patent: 4851080 (1989-07-01), Howe et al.
patent: 4855017 (1989-08-01), Douglas
patent: 4876217 (1989-10-01), Zdebel
patent: 4922756 (1990-05-01), Henrion
patent: 5016072 (1991-05-01), Greiff
patent: 5068203 (1991-11-01), Logsdon et al.
patent: 5083857 (1992-01-01), Hornbeck
patent: 5095752 (1992-03-01), Suzuki et al.
patent: 5097354 (1992-03-01), Goto
patent: 5121180 (1992-06-01), Beringhause et al.
patent: 5126812 (1992-06-01), Greiff
patent: 5172262 (1992-12-01), Hornbeck
patent: 5198390 (1993-03-01), MacDonald et al.
patent: 5199088 (1993-03-01), Magel
patent: 5203208 (1993-04-01), Bernstein
patent: 5221987 (1993-06-01), Laughlin
patent: 5226321 (1993-07-01), Varnham et al.
patent: 5235187 (1993-08-01), Arney et al.
patent: 5287082 (1994-02-01), Arney et al.
patent: 5316979 (1994-05-01), MacDonald et al.
patent: 5345824 (1994-09-01), Sherman et al.
patent: 5393375 (1995-02-01), MacDonald et al.
patent: 5397904 (1995-03-01), Arney et al.
patent: 5399415 (1995-03-01), Chen et al.
patent: 5426070 (1995-06-01), Shaw et al.
patent: 5427975 (1995-06-01), Sparks et al.
patent: 5428259 (1995-06-01), Suzuki
patent: 5449903 (1995-09-01), Arney et al.
patent: 5471332 (1995-11-01), Shiragaki et al.
patent: 5483158 (1996-01-01), van Heteren et al.
patent: 5488862 (1996-02-01), Neukermans et al.
patent: 5501893 (1996-03-01), Laermer et al.
patent: 5524153 (1996-06-01), Laor
patent: 5536988 (1996-07-01), Zhang et al.
patent: 5563343 (1996-10-01), Shaw et al.
patent: 5583373 (1996-12-01), Ball et al.
patent: 5610335 (1997-03-01), Shaw et al.
patent: 5611888 (1997-03-01), Bosch et al.
patent: 5611940 (1997-03-01), Zettler
patent: 5628917 (1997-05-01), MacDonald et al.
patent: 5629790 (1997-05-01), Neukermans et al.
patent: 5637189 (1997-06-01), Peeters et al.
patent: 5645684 (1997-07-01), Keller
patent: 5648618 (1997-07-01), Neukermans et al.
patent: 5670881 (1997-09-01), Arakawa et al.
patent: 5673139 (1997-09-01), Johnson
patent: 5719073 (1998-02-01), Shaw et al.
patent: 5726073 (1998-03-01), Zhang et al.
patent: 5739941 (1998-04-01), Knipe et al.
patent: 5759913 (1998-06-01), Fulford, Jr. et al.
patent: 5770465 (1998-06-01), MacDonald et al.
patent: 5798557 (1998-08-01), Salatino et al.
patent: 580408
Adams Scott
Chong John Matthew
Davis Tim
Lee Seung Bok (Chris)
Miller Scott
Blakely , Sokoloff, Taylor & Zafman LLP
Calient Networks, Inc.
Tamai Karl
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