Patent ID: 6206290
Filing Date: 2001-03-27
Classification: G06K

Abstract:
A light beam scanner for directing a light beam used to traverse a symbol to be read comprising:a light source;a mirror for reflecting light from the light source,a drive electrode for applying electrostatic force to the mirror to vary its position so that the direction of reflected light is varied;a pick-up electrode for sensing the position of the mirror; andfeedback circuitry for modifying the applied electrostatic force in response to the sensed mirror position,wherein the electrostatic force is periodically applied to the mirror by imposing a periodic voltage on the drive electrode and wherein the position of the mirror is sensed by detecting variations in the capacitance between the mirror and the pick-up electrode, andwherein a carrier signal is applied to the mirror and a voltage is induced on the pick-up electrode, which induced voltage corresponds to the carrier signal, amplitude modulated in response to changes in distance between the mirror and the pick-up electrode.