Patent ID: 7394839
Filing Date: 2008-07-01
Classification: B41J,H04N

Abstract:
1. An apparatus controlling a light power in a printing device having a main controller controlling a laser scanning unit, the apparatus comprising: a light generator generating light and disposed inside the laser scanning unit; a light power controller controlling a quantity of light generated by the light generator, the light power controller disposed inside the main controller, and the main controller disposed outside the laser scanning unit, the light power controller including: an error value detector subtracting a digital value of a feedback actual current from a digital value of an input current corresponding to a reference quantity of light emitted from a laser diode and outputting a digital value of an error current, a light-quantity adjusting unit generating a digital value of a light-emitting voltage for emitting light from the laser diode using the digital value of the error current, the light-quantity adjusting unit being a proportional integral controller, a value continuous converter converting the digital value of the light-emitting voltage into an analog signal and outputting the analog signal to the light generator, the light generator generating the light in response to the analog signal and outputting an actual current, and a continuous discrete converter converting the actual current into a digital value of the actual current and determining the feedback actual current; and a clamping unit clamping the digital value of the light-emitting voltage generated by the light-quantity adjusting unit at a constant level.