Abstract: An image forming apparatus to perform mono printing and color printing having different printing speeds and enhance printing performance includes an image forming unit to perform the color printing and the mono printing, and a control unit to determine whether to change a printing speed by comparing an amount of printing to be processed with a predetermined critical value and, if it is determined to change the printing speed, controlling the image forming unit to perform printing according to the amount of printing to be processed by switching a printing speed from printing at a relatively slow printing speed to printing at a relatively fast printing speed.

Abstract: A method for color registration includes determining if color registration is necessary, and if color registration is necessary, rotating an image forming medium and setting an optimum luminance of a registration sensor with respect to a rotating surface of the image forming medium, confirming an area with an undesirable surface condition on the image forming medium using luminance detected with respect to the rotating surface of the image forming medium during the setting of the optimum luminance, forming a preset mark for color registration adjustment excluding the area confirmed to have an undesirable surface condition, and carrying out color registration adjustment using the optimum luminance set with respect to the formed mark.

Abstract: An image forming apparatus to perform mono printing and color printing having different printing speeds and enhance printing performance includes an image forming unit to perform the color printing and the mono printing, and a control unit to determine whether to change a printing speed by comparing an amount of printing to be processed with a predetermined critical value and, if it is determined to change the printing speed, controlling the image forming unit to perform printing according to the amount of printing to be processed by switching a printing speed from printing at a relatively slow printing speed to printing at a relatively fast printing speed.

Abstract: A method for color registration includes determining if color registration is necessary, and if color registration is necessary, rotating an image forming medium and setting an optimum luminance of a registration sensor with respect to a rotating surface of the image forming medium, confirming an area with an undesirable surface condition on the image forming medium using luminance detected with respect to the rotating surface of the image forming medium during the setting of the optimum luminance, forming a preset mark for color registration adjustment excluding the area confirmed to have an undesirable surface condition, and carrying out color registration adjustment using the optimum luminance set with respect to the formed mark.

Abstract: A color registration method of an image forming apparatus, including forming a plurality of front detection marks corresponding to a plurality of colors on a transfer belt, forming a first rear detection mark to at least one of the plurality of colors, except at least one of the plurality of colors, using a color registration reference, and performing auto color registration (ACR) to align the colors on the basis of the first rear detection mark.

Abstract: A color registration method of an image forming apparatus, including forming a plurality of front detection marks corresponding to a plurality of colors on a transfer belt, forming a first rear detection mark to at least one of the plurality of colors, except at least one of the plurality of colors, using a color registration reference, and performing auto color registration (ACR) to align the colors on the basis of the first rear detection mark.

Abstract: A method and apparatus for compensating for scanning skew formed in an electrophotographic color image forming device. The method includes the step of making a scanning light that forms a scanning line ascend or descend in a sub-scanning direction within a range of one dot, and scanning the ascending or descending light in the main scanning direction. Also, the apparatus includes an optical scanner control unit which controls an optical scanning unit so that a scanning light that forms a scanning line ascends or descends in a sub-scanning direction within a range of one dot and the ascending or descending light is scanned in the main scanning direction.

Abstract: A halftone processing method for correcting the variation in light intensity on a photoconductive drum and an apparatus using the same, wherein the method includes the steps of preparing a plurality of dithering functions, detecting the position where image data for forming an electrostatic latent image is scanned on the photoconductive drum, selecting one of the plurality of dithering functions according to the detected scanning position, and halftone-processing the image data using the selected dithering function. Accordingly, the halftone processing method improves print quality by increasing light intensity at the edges of a photoconductive drum by permitting the laser printer to be halftone-processed using dithering functions whose critical values are different for the center and the edges of the photoconductive drum.

Abstract: A method and apparatus are provided for controlling a fixing condition of a printer according to the size and type of paper to be printed in order to improve print quality. The apparatus and method include setting a fixing condition according to a selected paper property of a printer driver, measuring a resistance of a paper being printed, comparing a paper property corresponding to the measured paper resistance with the selected paper property of the printer driver, and resetting the fixing condition according to the paper property corresponding to the measured paper resistance if the paper property corresponding to the measured paper resistance is different from the selected paper condition of the printer driver.

Abstract: A temperature control method for use in a fusing device of image forming apparatus having a fusing roller and a heater heating the fusing roller, including: sensing a surface temperature T of the fusing roller at one of when the image forming apparatus is turned on, when the image forming apparatus begins a normal operation from a power saving operation, and when a cover of the image forming apparatus is closed after being opened; comparing the sensed surface temperature T of the fusing roller with a set temperature; driving the heater until the surface temperature T reaches a first target temperature Tt1 when the sensed surface temperature T is below the set temperature; and driving the heater until the surface temperature T reaches a second target temperature Tt2 when the sensed surface temperature T is over the set temperature.

Abstract: A fusing system for use in an image forming apparatus has a fusing temperature control unit having a controller which controls the surface temperature ‘T’ of the fusing roller by detecting the surface temperature ‘T’ in accordance with a predetermined temperature control period ‘t0’; comparing the surface temperature ‘T’ with a preset target temperature ‘Tt’; turning on and off the heater in accordance with a maximum power supply time ‘Max ON-time’ and a minimum power cutoff time ‘Min OFF-time’ when the surface temperature ‘T’ is lower than the target temperature ‘Tt’; and turning on and off the heater in accordance with a preset minimum power supply time ‘Min ON-time’ when the surface temperature ‘T’ is higher than the target temperature ‘Tt’.

Abstract: A fusing system and a temperature control method thereof for use in an image forming apparatus. The fusing system includes a control unit having a controller. The controller determines whether to initiate a heater driving-start timing, on the basis of one of a first time t1 and a third time t3, and a second time t2, when a sheet of printing paper is picked up by the pickup roller, or when a leading end of the sheet of the printing paper picked up by the pickup roller operates the paper jam sensor, the first time t1 being a time when the sheet of printing paper is picked up to a point of time when the sheet of printing paper arrives at the fusing roller, the second time t2 being a time required until a heat generated from the heater arrives at a surface of the fusing roller, and the third time t3 being a time from when the sheet of printing paper operates the paper jam sensor to when the sheet of printing paper is arrives at the fusing roller.

Abstract: A method and apparatus for compensating for scanning skew formed in an electrophotographic color image forming device. The method includes the step of making a scanning light that forms a scanning line ascend or descend in a sub-scanning direction within a range of one dot, and scanning the ascending or descending light in the main scanning direction. Also, the apparatus includes an optical scanner control unit which controls an optical scanning unit so that a scanning light that forms a scanning line ascends or descends in a sub-scanning direction within a range of one dot and the ascending or descending light is scanned in the main scanning direction.

Abstract: A halftone processing method for correcting the variation in light intensity on a photoconductive drum and an apparatus using the same, wherein the method includes the steps of preparing a plurality of dithering functions, detecting the position where image data for forming an electrostatic latent image is scanned on the photoconductive drum, selecting one of the plurality of dithering functions according to the detected scanning position, and halftone-processing the image data using the selected dithering function. Accordingly, the halftone processing method improves print quality by increasing light intensity at the edges of a photoconductive drum by permitting the laser printer to be halftone-processed using dithering functions whose critical values are different for the center and the edges of the photoconductive drum.

Abstract: A method and apparatus are provided for controlling a fixing condition of a printer according to the size and type of paper to be printed in order to improve print quality. The apparatus and method include setting a fixing condition according to a selected paper property of a printer driver, measuring a resistance of a paper being printed, comparing a paper property corresponding to the measured paper resistance with the selected paper property of the printer driver, and resetting the fixing condition according to the paper property corresponding to the measured paper resistance if the paper property corresponding to the measured paper resistance is different from the selected paper condition of the printer driver.

Abstract: A method of controlling a fusing temperature of an electrophotographic imaging apparatus includes controlling the fusing temperature of a fusing roller which is subject to a delayed response to heating due to a rubber layer formed on a surface of the fusing roller with a predetermined thickness. In the method, after the fusing temperature of the fusing roller has reached a predetermined target fusing temperature, a power corresponding to an offset value or an offset power supply ratio is supplied to a heater for a predetermined power control period or a predetermined offset control period to maintain the fusing temperature of the fusing roller. A thermal loss in the fusing apparatus during a print mode is compensated by existing power control methods, and the fusing temperature of the fusing roller is maintained at the target fusing temperature by periodically supplying a predetermined amount of the power to the heater, so that a quality of an image fused onto a recording medium is improved.

Abstract: A method and apparatus to control an image input and a recording-medium supply of an image forming apparatus. An aspect of the method comprises periodically generating synchronized demand of an image input into the exposure unit and supplying of a recording medium to the transfer unit, and inputting an image into the exposure unit according to the synchronized demand on image input and supplying a recording medium to the transfer unit according to the synchronized demand on recording-medium supply.

Abstract: A fusing system for use in an image forming apparatus has a fusing temperature control unit having a controller which controls the surface temperature ‘T’ of the fusing roller by detecting the surface temperature ‘T’ in accordance with a predetermined temperature control period ‘t0’; comparing the surface temperature ‘T’ with a preset target temperature ‘Tt’; turning on and off the heater in accordance with a maximum power supply time ‘Max ON-time’ and a minimum power cutoff time ‘Min OFF-time’ when the surface temperature ‘T’ is lower than the target temperature ‘Tt’; and turning on and off the heater in accordance with a preset minimum power supply time ‘Min ON-time’ when the surface temperature ‘T’ is higher than the target temperature ‘Tt’.

Abstract: A method and apparatus for driving a belt is provided. Included is a method and apparatus for searching for a home position of a steering roller for adjusting a position of the belt in a widthwise direction of the belt and placing the steering roller in the home position. The steering roller is moved from the home position to a balance point, in which an amount of variation of the belt in the widthwise direction is less than a predetermined value, or moved to a position of the steering roller that corresponds to a previously driven final position of the belt. The belt is driven in this state such that the amount of initial weaving of the belt is reduced. Thus, an amount of initial weaving of the belt when the belt is driven can be minimized such that a time to obtain images with suitable registration can be greatly reduced.

Abstract: A fusing system and a temperature control method thereof for use in an image forming apparatus. The fusing system comprises a control unit having a controller. The controller determines whether to initiate a heater driving-start timing, on the basis of one of a first time t1 and a third time t3, and a second time t2, when a sheet of printing paper is picked up by the pickup roller, or when a leading end of the sheet of the printing paper picked up by the pickup roller operates the paper jam sensor, the first time t1 being a time when the sheet of printing paper is picked up to a point of time when the sheet of printing paper arrives at the fusing roller, the second time t2 being a time required until a heat generated from the heater arrives at a surface of the fusing roller, and the third time t3 being a time from when the sheet of printing paper operates the paper jam sensor to when the sheet of printing paper is arrives at the fusing roller.