Patent ID: 7161273

Claim:
A method of controlling operating voltage characteristics of an electrostatic actuator, comprising: providing the electrostatic actuator comprising: a first electrode; a second electrode facing the first electrode; and an insulating film formed on at least one of the first electrode and the second electrode, wherein the second electrode comes into contact with the first electrode through the insulating film when a voltage is applied between the first electrode and the second electrode; and selecting a contact area of the insulating film with the first electrode, the second electrode, or another insulating film such that a shift amount of the operating voltage characteristics depending on the thickness of the insulating film is substantially offset by a shift amount of the operating voltage characteristics depending on the contact area of the insulating film with the first electrode, second electrode, or another insulating film, wherein at least one protrusion is disposed on a contact surface of at least one of the first electrode, second electrode, and the insulating film, and the contact area is selected by a size and shape of the at least one protrusion, wherein the thickness of the at least one insulating film is set to 2000 to 2500 angstroms, the height of the at least one protrusion is set to 400 to 600 angstroms, the diameter of the at least one protrusion is set to 25 to 35 micrometers, and the at least one protrusion is formed with pitches set to 100 to 110 micrometers.