High frequency pulse width modulation driver, particularly useful for electrostatically actuated MEMS array

An actuator and control system, comprising:

• an electrostatic actuator comprising a first electrode fixed on a first mechanical element and a second electrode fixed in opposition to said first electrode on a second mechanical element which is movable with respect to said first mechanical element;
• first determining means for determining a duty cycle of a bipolar electrostatic signal to be applied between said two electrodes to achieve a desired separation of said two mechanical elements;
• and
• first applying means for applying between said two electrodes said bipolar electrostatic signal having said duty cycle.

A system including an array of electrostatic actuators, comprising:

• a plurality of electrostatic actuators arranged in an array and each including a respective first mechanical element with a respective affixed first electrode and a respective second mechanical element with a respective an affixed second electrode, said two mechanical elements of each of said electrostatic actuators being movable with respect to each other;
• a counter driven by a repetitive trigger signal;
• an amplifier receiving a high-order bit of said counter and creating a first drive signal applied to all of said first electrodes;
• and
• a plurality of control circuits associated with respective ones of said actuators and each including
• a respective register storing a respective delay value,
• a respective comparator comparing said stored delay value with lower-order bits of said counter, and
• a respective latch triggered by an output of said respective comparator latching said high-order bit of said respective counter to produce a respective delayed drive signal, said second electrode of the associated one of said actuators being driven according to said respective delayed drive signal.

An electrostatically actuated element, comprising:

• a mechanical element tiltable about an axis and including a first electrode extending across said axis;
• second and third electrodes in opposition to portions of said first electrode on opposed sides of said axis;
• a first electrical drive applying a first periodic signal to said first electrode;
• a second electrical drive applying a second periodic signal to one of said second and third electrodes that is phase shifted from said first periodic signal by a controllable phase shift;
• and
• a controller setting a value of said controllable phase shift to control a degree of tilting of said mechanical element.