An electrostatic actuator having two-dimensional in-plane motion of a monolithic element suspended by flexures which is unstable in the open-loop and uses feedback control to operate. By adding a common bias voltage to each of the stator electrodes when the translator and stator are in the unstable equilibrium position, repulsion can be reduced to zero while the in-plane force remains in unstable equilibrium. Stabilizing the in-plane force at the unstable equilibrium position is achieved by shifting the electrical phase of the stator potential distribution in a direction to produce an in-plane force which opposes motion of the translators away from the equilibrium position. Linear control and pulse width modulation control permit altering the phase by less than the stator pitch. The drive electrodes of the translator and stator are used as position sensors for in-plane and out-of-plane relative displacements of the translator and stator concurrent with operation of the motor using either pulse-width modulation or linear control.
A micro-motor position controller utilizes a ratiometric position sensor that operates independent of any reference voltage sources. A first capacitor and a second capacitor in a micro-motor are connected in series and form one section of a capacitive bridge. The other section of the bridge is ground. A first sinusoidal voltage is created at the top of the capacitive bridge and a second sinusoidal voltage that is 180 degrees out of phase from the first sinusoidal voltage is created at the bottom of the bridge. The motor is moved and the capacitance values of the first and second capacitors are changed until, ultimately, there is no voltage present on the armature of the motor. The voltage level present at the armature is measured relative to AC ground, and is used as an error signal to control the position of the motor.
An electrostatic actuator includes first and second electrode portions disposed at predetermined intervals, each electrode portion including one or more series of electrodes arranged successively in a predetermined direction; a slider disposed between the first and second electrode portions and having electrode portions at side faces opposed to the first and second electrode portions, the slider being movable in the predetermined direction; an electrostatic capacitance detecting circuit configured to detect electrostatic capacitances between each series of electrodes of the first and second electrode portions and the electrode portions of the slider; and a driving circuit configured to drive the slider in the predetermined direction by applying voltages between selected series of electrodes of one of the first and second electrode portions and the electrode portions of the slider, said selected series of electrodes being selected based on a detected result of the electrostatic capacitance detecting circuit.
An electrostatic actuator includes first and second electrode portions disposed at predetermined intervals, each electrode portion including one or more series of electrodes arranged successively in a predetermined direction; a slider disposed between the first and second electrode portions and having electrode portions at side faces opposed to the first and second electrode portions, the slider being movable in the predetermined direction; an electrostatic capacitance detecting circuit configured to detect electrostatic capacitances between each series of electrodes of the first and second electrode portions and the electrode portions of the slider; and a driving circuit configured to drive the slider in the predetermined direction by applying voltages between selected series of electrodes of one of the first and second electrode portions and the electrode portions of the slider, said selected series of electrodes being selected based on a detected result of the electrostatic capacitance detecting circuit.
Double gate transistors having at least two polysilicon patterns on a thin body used as an active region and methods of forming the same are provided. Embodiments of the transistors and methods provided are capable of enhancing current drivability of a semiconductor memory device using polysilicon patterns having different impurity concentrations from each other. In some embodiments an active region is protruded from a semiconductor substrate, an impurity diffusion region is formed in the active region, and a gate insulating pattern and a gate pattern are sequentially stacked on the active region. In these embodiments, the gate pattern may include polysilicon patterns having different impurity concentrations from each other.
An apparatus includes a first capacitive sensor connected to a first supply voltage, a second capacitive sensor connected to a second supply voltage, a sensing circuit for producing a sense voltage in response to current flowing in the first and second capacitive sensors, a first mixer for combining the sense voltage with a first reference voltage to produce a first signal representative of in-plane displacement between electrodes of the first and second capacitive sensors, and a second mixer for combining the sense voltage with a second reference voltage to produce a second signal representative of out-of-plane displacement between the electrodes of the first and second capacitive sensors.
