Abstract: A method and apparatus for controlling the power of laser diodes are provided. The apparatus includes an output voltage sensor, which senses output voltages of at least two laser diodes and outputs the output voltages to an optical power controller. The optical power controller generates control voltages for controlling the at least two laser diodes by performing proportional-integral (PI) control on error voltages between reference voltages and the output voltages received from the output voltage sensor.

Abstract: A method and apparatus controlling a light power, the apparatus including a light power controller, which controls a quantity of light and disposed inside the main controller disposed outside the laser scanning unit, and a light generator, which generates light and disposed inside the laser scanning unit.

Abstract: A laser scanning unit includes a housing; an optical system disposed in the housing and including an optical source which emits a laser beam, a polygonal mirror which scans the laser beam, and a plurality of optical elements which image the laser beam on an image surface; a motor disposed in the housing and which rotates the polygonal mirror; and a motor drive chip disposed outside of the housing and which uses a sensorless algorithm to control a rotation speed of the motor.

Abstract: An apparatus for controlling temperature of an image forming apparatus includes: a temperature sensing unit including a plurality of temperature sensors to sense temperatures of respective parts of the image forming apparatus; a paper feeding time converting unit converting the sensed temperatures into printing paper feeding times according to a fuzzy rule for converting temperatures into paper feeding times; and a paper feeding unit feeding the printing paper in accordance with the converted paper feeding times. The inner temperature of the image forming apparatus is sensed by a plurality of temperature sensors so that the entire temperature of the image forming apparatus can be controlled. A paper feeding time is adjusted so that the temperature of the image forming apparatus can be effectively controlled without additional mechanical design.

Abstract: A method of controlling an output of a laser diode and an output control device of a laser diode having a function of changing the control parameter are provided. The method includes setting an output auto-control section of a laser diode, sampling a digital output voltage of the laser diode during the output auto-control section, calculating a difference between a maximum value and a minimum value of the sampled digital output voltage, and selecting a new control parameter when the difference is larger than a reference value. A control parameter used in an output control device of a laser diode is automatically set corresponding to a characteristics of each laser diode, such that it is possible to prevent a phenomenon in which an optical power level is fluctuated when the control parameter set according to a single characteristic of the laser diode is improper due to a fixed control parameter in a conventional optical power control device.

Abstract: An apparatus and method of controlling a stepper motor, includes a torque calculator to calculate torque operated on the stepper motor and to output to a controller a driving current setting signal corresponding thereto. The controller outputs to a driver a control signal to apply variable driving current based on the driving current setting signal to the stepper motor. The driver drives the stepper motor based on the control signal inputted from the controller. Accordingly, overheating and inaccurate operations of a control IC (the controller) and the stepper motor may be prevented, and driving characteristics such as low power consumption, low vibration and low noise of the stepper motor may be improved.

Abstract: A method of reducing consumption of a developer used in an electrophotographic processor that forms a latent electrostatic image on a charged photosensitive object using a laser exposure unit for outputting a laser beam, the method including adjusting a power of the laser beam to match a user-selected density of an output image so as to adjust an electric potential between an image region and a non-image region of the latent electrostatic image, wherein the consumption of the developer is reduced, and an electrophotographic processor performing the method.

Abstract: A method and apparatus for controlling the power of laser diodes are provided. The apparatus includes an output voltage sensor, which senses output voltages of at least two laser diodes and outputs the output voltages to an optical power controller. The optical power controller generates control voltages for controlling the at least two laser diodes by performing proportional-integral (PI) control on error voltages between reference voltages and the output voltages received from the output voltage sensor.

Abstract: A method and apparatus controlling a light power, the apparatus including a light power controller, which controls a quantity of light and disposed inside the main controller disposed outside the laser scanning unit, and a light generator, which generates light and disposed inside the laser scanning unit.

Abstract: A laser scanning unit includes a housing; an optical system disposed in the housing and including an optical source which emits a laser beam, a polygonal mirror which scans the laser beam, and a plurality of optical elements which image the laser beam on an image surface; a motor disposed in the housing and which rotates the polygonal mirror; and a motor drive chip disposed outside of the housing and which uses a sensorless algorithm to control a rotation speed of the motor.

Abstract: A sensorless speed control apparatus and method for a brushless dc (BLDC) motor. A speed detection unit detects fluxes of respective phases of the BLDC motor, measures a period of the detected flux changes, and determines a speed of the BLDC motor. A subtractor subtracts an inputted reference speed and the detected speed outputted from the speed detection unit, and outputs an error speed. A speed controller outputs a reference current corresponding to the error speed outputted from the subtractor. A current controller outputs a control signal for controlling the switching operations of an inverter based on the reference current outputted from the speed controller. The inverter applies a current of variable frequency to the respective phases of the motor based on the control signal outputted from the current controller, and drives the motor.

Abstract: An apparatus and method of controlling a stepper motor, includes a torque calculator to calculate torque operated on the stepper motor and to output to a controller a driving current setting signal corresponding thereto. The controller outputs to a driver a control signal to apply variable driving current based on the driving current setting signal to the stepper motor. The driver drives the stepper motor based on the control signal inputted from the controller. Accordingly, overheating and inaccurate operations of a control IC (the controller) and the stepper motor may be prevented, and driving characteristics such as low power consumption, low vibration and low noise of the stepper motor may be improved.