Masayuki Sekimura

Anisotropic etching of surfactant-added TMAH solution

The anisotropic silicon etching characteristics of surfactant-added tetramethyl ammonium hydroxide (TMAH) solution were investigated. It was found that the etch rate of the [110] crystal plane abruptly decreases by more than one order of magnitude and that the etch rate ratio of the etch rate of the [100] crystal plane to the etch rate of the [110] crystal plane is reversed. The roughness of the etched surface of the [110] crystal plane was improved by the addition of surfactant. A peculiar figure was not obtained at wagon wheel pattern etching. Thus, it was visually observed that the anisotropy of surfactant-added TMAH solution was different from that of pure TMAH solution. As a result of the reversal of the etch rate ratio, undercut of convex corners was reduced and slanted [110] planes at 45/spl deg/ to the surface of the [100] crystal plane were obtained.

Attachment/detachment electrostatic micro actuators for pan-tilt drive of a micro CCD camera

Newly developed linear electrostatic micro actuators employing an attachment/detachment mechanism and fabricated by a bulk silicon micromachining process are described. The moving part (slider) of these actuators is sandwiched between two glass plates whose surfaces have many electrodes (fixed electrodes), is attached to these fixed electrodes by turns up and down, and is actuated in the course of the linear motion. A feature of these actuators is that anti-friction bearings are not required and the influence of friction is reduced significantly. Several difficulties have been identified regarding attachment/detachment operation actuators. The accumulation of charge caused by contact between each stator and slider is one of the most difficult problems, and it can lead to complete actuator failure. The newly developed actuators have micro pyramid stoppers which prevent the accumulation of charge on both surfaces of the moving part. When a diving voltage of about 80 [V] is applied, the slider moves successfully with a /spl plusmn/1 [mm] stroke at a speed of 1.0 mm/sec under the condition of no load. The authors further apply these actuators to a micro pan-tilt mechanism for altering the vision angle of a micro CCD camera and experimentally confirm their practical utility.

Damping of micro electrostatic torsion mirror caused by air-film viscosity

A method of analyzing the damping characteristics of electrostatically driven torsion mirror actuators which have deep grooves on their electrodes is described. The damping force is caused by viscous friction of the gas film between a moving mirror plate and the electrodes. The grooves decrease the damping force and enable the moving plate to be driven at high speed and low driving voltage. To calculate the damping force correctly, it is necessary to consider the viscous friction not only on the moving plate and electrodes, but also on the sidewalls of the grooves. For that purpose, the idea of hydraulic mean depth is introduced and is applied to the Reynolds equation. The calculated damping force shows good agreement with the measured damping force of the developed torsion mirror actuator for optical heads.

Electrostatic linear micro actuators with vibrating motion for pan-tilt drive of a micro CCD camera

Newly developed linear electrostatic micro actuators employing a vibrating motion and fabricated by a bulk silicon micromachining process are described. The moving part (slider) of these actuators is sandwiched between two glass plates whose surfaces have many electrodes (fixed electrodes), is attached and detached to these fixed electrodes by turns, and actuates linearly on a macroscopic level. A feature of these actuators is that the influence of friction is reduced significantly and a large stroke is achieved. However, several difficulties have been identified regarding attachment/detachment operation actuators. The interactive forces, including the accumulation of charge caused by contact between each stator and slider create one of the most difficult problems. Our developed actuators incorporate micro pyramid stoppers, which prevent the accumulation of charge and other interactive forces, on both surfaces of the moving parts. The casing size of the prototype is 8/spl times/8/spl times/1.2 mm and achieves a 2 mm range of movement. The minimum driving voltage is 60 V and maximum velocity is 2.0 mm/s. The behavior of the slider is not simple and further analysis is very important in order to improve positioning accuracy, increase output force, and decrease driving voltage. The characteristics of the actuator (Stepping Model) obtained by experiments is reported. The authors further apply these actuators to a micro pan-tilt mechanism for altering the vision angle of a micro CCD camera and experimentally confirm their practical utility.

Electrostatic linear micro actuator with vibrating motion (application to the focusing mechanism of a miniature CCD camera)

A newly developed linear electrostatic micro actuator mechanism employing a vibrating motion is described. Features of this mechanism are that anti-friction bearings are not required, the influence of friction is reduced significantly, and a large stroke is achieved. The moving part (Slider) of this actuator is sandwiched between fixed electrodes (Stator), is alternately attached and detached to these fixed electrodes, and actuates linearly on a macroscopic level. Several difficulties have been identified regarding actuators operated by attachmen/ detachment. The interactive forces, including the accumulation of charge caused by contact between each slider and stator, create one of the most difficult problems. Our developed actuator incorporates micro stoppers, which prevent the accumulation of charge and other interactive forces on the surface of the slider or the stator. A voltage supply pattern such that the positive and negative charge appear alternately, is employed. The first prototype, casing size ...