Patent ID: 6940207

Claim:
A micromachined moving device comprising: fixed electrode means; moving electrode means disposed opposite at a distance from said fixed electrode means, said moving electrode means being resiliently supported; and an AC drive circuit connected to said fixed electrode means and said moving electrode means, for generating an AC drive voltage for application across said fixed electrode means and said moving electrode means in response to an input control signal; wherein said AC drive circuit responds to said input control signal to apply said AC drive voltage across said fixed electrode means and said moving electrode means to drive said moving electrode means by electrostatic force into and out of contact with said fixed electrode plate; and wherein said AC drive circuit comprises: an oscillator for generating an AC signal of periodically varying polarity as at least part of said AC drive voltage; a variable gain amplifier for amplifying said AC signal from said oscillator and for outputting said AC drive voltage; and a control voltage generator responsive to said input control signal to generate a gain control signal which controls the gain of said variable gain amplifier to amplify said AC signal to a first voltage for attracting said moving electrode means into contact with said fixed electrode means for a predetermined period and thereafter amplify said AC signal to a second voltage lower than said first voltage for holding said moving electrode means in contact with said fixed electrode means until said input control signal is turned OFF.