US Patent 7609426 Image scanning apparatus

An image scanning apparatus for embodying an image using visible lights apparatus includes a scanning unit for irradiating line scan light; a power source for generating voltage for driving the scanning unit; a light detector for detecting duty that is a variation ratio of line scan light with respect to time; and a servo-loop for comparing the detected duty with a preset value, calculating a magnitude of the voltage for driving the scanning unit, and applying voltage, which is controlled depending on the calculated voltage magnitude, to the scanning unit.