Abstract: A method and apparatus for compensating image skew and an electro-photographic image forming apparatus including the same are provided. Image skew of a toner image transferred onto a paper is compensated for by inclining a photosensitive medium onto which a light beam is scanned to be parallel to a scanning line of the light beam. A first inclination member including a first inclined surface facing upward and a second inclination member including a second inclined surface contacting and facing the first inclined surface are provided, wherein a position of a shaft of the photosensitive medium is adjusted by moving at least one of the first and second inclination members. Image skew of a toner image is sensed, and a photosensitive medium onto which a light beam is scanned is inclined to correspond to a scanning line skew of the light beam.

Abstract: A waste toner transfer apparatus in an electrophotographic printer transfers waste toner removed by a cleaning unit from an image holding body where a toner image is temporarily held to a waste toner storage container. The waste toner transfer apparatus includes a duct connecting the cleaning unit and the storage container, a transfer unit installed in the duct and transferring the waste toner to the storage container, and an agitation member installed in the duct to move therein and guide the waste toner from the cleaning unit to the transfer unit.

Abstract: A transfer unit-fixing apparatus to integrally fix a transfer unit on a door, and an image forming device having the same are disclosed. The transfer unit-fixing apparatus includes a position fixing unit to pivotally support a first part of the transfer unit on the door and a locking unit to lock a second part of the transfer unit to the door. The transfer unit can be easily assembled and disassembled to and from the door by the position fixing unit and the locking unit, and thus the image forming device can be easily assembled, maintained and repaired.

Abstract: An image forming apparatus including a main body, a photoconductive unit disposed in the main body to develop an image, a transferring unit removably disposed in the main body in contact with the photoconductive unit to transfer the image from the photoconductive unit onto a recording medium, a locking/releasing unit to lock and unlock a mounting position of the transferring unit with respect to the photoconductive unit, and a checking unit to check whether the transferring unit is mounted by the locking/releasing unit. Accordingly, even if the user may inadvertently operate the image forming apparatus while not operating the locking/releasing unit so that the transferring unit and the photoconductive unit are not fixed to each other, the image forming apparatus notifies the user.

Abstract: An electrophotographic image forming apparatus for enhancing color registration is provided. The electrophotographic image forming apparatus includes a developing unit including a photosensitive medium, an image transferring device, and a paper feeding device. The image transferring device includes a pair of conveying rollers, a conveying belt, and a plurality of transfer rollers. The conveying belt is supported by the conveying rollers and rotates around the conveying rollers and conveys a recording medium by attaching a recording medium to a surface thereof. The plurality of transfer rollers are disposed inside the conveying belt and form a transfer nip between the recording medium and the photosensitive medium. The paper feeding device provides the recording medium to the image transferring device.

Abstract: A developing cartridge includes a housing having a photosensitive medium, and a protective cover movable between a first position where the protective cover covers the photosensitive medium and a second position where a part of the photosensitive medium is exposed. A guide unit guides the protective cover to prevent exceeding a range occupied by the housing when the protective cover is moved to the first and second positions.

Abstract: An image registration apparatus and method are provided. The image alignment registration apparatus includes a plurality of exposing units which form electrostatic latent images by scanning light; a sensing unit which senses color test patterns to correct image alignment; an error detecting unit which detects alignment errors of test patterns in response to a sensing result of the sensing unit; and an exposure time setting unit which determines the exposure time required to form an electrostatic latent image in each of the exposing units in response to errors detected by the error detecting unit, wherein each of the exposing units form the electrostatic latent image according to the exposure time determined by the exposure time setting unit. Accordingly, by controlling the exposure time for forming images in a tandem type image forming apparatus, image alignment errors are corrected.

Abstract: A developer-driving device and an image forming apparatus having the same are provided. The developer-driving device includes a photosensitive drum-driving unit that rotates a photosensitive drum and a developing roller-driving unit that rotates a developing roller. Each of the photosensitive drum-driving unit and the developing roller-driving unit includes a one-way power transmission unit. The one-way power transmission unit idles when a developer is being mounted on a main body and transmits power to the photosensitive drum and the developing roller after the developer is mounted on the main body.

Abstract: A fusing unit used with a color laser printer includes a pair of rollers which heat and press a sheet of paper, onto which an image is transferred, and fuse the transferred image on the sheet of paper, and plastic mold bearings which rotatably support the rollers to be centered on frames.

Abstract: A laser scan unit for an image forming apparatus is provided that compensates for an error of the irradiating position of a laser beam on a photoconductive medium, such as the error caused by processing errors or assembling errors of component parts. The laser scan unit includes a frame, a laser scan unit mounted in the frame and projecting a laser beam on a photoconductive medium according to printing data, and a control unit tilting the laser scan unit on the frame to adjust the irradiation position of the laser beam on the photoconductive medium in main scanning and sub scanning directions.

Abstract: A pickup error-sensing apparatus of an image forming apparatus and method therefor. The pickup error-sensing apparatus includes a sensing actuator rotatably disposed on a frame with respect to a paper cassette, displaceable when sheets of paper are loaded in the cassette, a paper sensor unit outputting a paper loading and unloading signals according to the displacement of the sensing actuator, a sensing actuator-operating unit operating the sensing actuator to allow the paper sensor unit to output the paper unloading signal when a pickup roller carries out a pickup movement, and a control unit determining whether the paper unloading signal is output when the pickup roller carries out the pickup movement, and determining occurrence of a pickup error to stop the image forming apparatus when the paper unloading signal is not output. The apparatus and method sense the pickup error generated from inadequate movement of the pick-up roller without installing a separate paper sensor.

Abstract: A pickup error-sensing apparatus of an image forming apparatus and method therefor. The pickup error-sensing apparatus includes a sensing actuator rotatably disposed on a frame with respect to a paper cassette, displaceable when sheets of paper are loaded in the cassette, a paper sensor unit outputting a paper loading and unloading signals according to the displacement of the sensing actuator, a sensing actuator-operating unit operating the sensing actuator to allow the paper sensor unit to output the paper unloading signal when a pickup roller carries out a pickup movement, and a control unit determining whether the paper unloading signal is output when the pickup roller carries out the pickup movement, and determining occurrence of a pickup error to stop the image forming apparatus when the paper unloading signal is not output. The apparatus and method sense the pickup error generated from inadequate movement of the pick-up roller without installing a separate paper sensor.

Abstract: A foreign substance prevention unit use with an electro-photographic printer is installed over a waste toner injection hole such that it closes the waste toner injection hole when a photosensitive medium is separated from a main body of the electro-photographic printer, and opens the waste toner injection hole when the photosensitive medium is installed in the main body of the electro-photographic printer. The foreign substance prevention unit is formed of an elastic material.

Abstract: A waste toner transfer apparatus in an electrophotographic printer to transfer waste toner removed by a cleaning unit and transferred to a waste toner storage container. The waste toner transfer apparatus includes a duct connecting the cleaning unit and the waste toner storage container, a conveying coil having a spiral shape which is installed in the duct and rotates, and an insertion member inserted in the conveying coil.

Abstract: An apparatus is provided for fixing shaft of photosensitive body and an image forming device including the apparatus. The apparatus includes a fixed supporting part formed at a frame, and rotatably supporting a first end of a shaft of at least one photosensitive body. A movable supporting part is formed at the frame to be movable between a first position and a second position, and rotatably supporting a second end of the shaft of the photosensitive body. An operating part operates to move the movable supporting part between the first position and the second position. The fixed supporting part and the movable supporting part fix the shaft of the photosensitive body, and the movable supporting part works together with opening and closing operation of the cover. The shaft of the photosensitive body is fixed in the proper position, but also a corresponding image forming cartridge is easily assembled and disassembled in the frame of the main body when the image forming cartridge is mounted in the frame.

Abstract: An electrophotographic printer including a pre-erasing unit. The pre-erasing unit includes a pre-erasing lamp to irradiate light, and a pre-transfer erasing lens to induce the light generated from the pre-transfer erasing lamp to the photosensitive drum, movably installed such that it moves to an erasure position at which the pre-transfer erasing lens is close to the photosensitive drum for erasure, and moves to a retracted position spaced apart from the photosensitive drum so as not to interfere therewith when the photosensitive drum unit is being mounted or dismounted. The pre-erasing unit may further include an elastic member to provide elasticity in a direction in which the pre-transfer erasing lens moves to the retracted position.

Abstract: An electrophotographic includes a main frame, a photosensitive drum unit having a photosensitive drum and vertically detachably installed on the main frame, a plurality of development units each having a developing roller and detachably installed on the main frame while sliding in a horizontal direction, and a first door openably installed for mounting or dismounting the plurality of development units.

Abstract: A waste toner transfer apparatus in an electrophotographic printer for transferring waste toner removed by a cleaning unit from an image holding body, where a toner image is temporarily held, to a waste toner storage container. The waste toner apparatus includes a duct for connecting the cleaning unit and the waste toner storage container, a transfer unit installed in the duct to transfer the waste toner, a guide portion provided at an outlet of the duct to be inclined downward to guide the waste toner toward the waste toner storage container, and an agitation member installed on the guide portion and moving to prevent the waste toner from accumulating on the guide portion.

Abstract: A pickup error-sensing apparatus of an image forming apparatus and method therefor. The pickup error-sensing apparatus includes a sensing actuator rotatably disposed on a frame with respect to a paper cassette, displaceable when sheets of paper are loaded in the cassette, a paper sensor unit outputting a paper loading and unloading signals according to the displacement of the sensing actuator, a sensing actuator-operating unit operating the sensing actuator to allow the paper sensor unit to output the paper unloading signal when a pickup roller carries out a pickup movement, and a control unit determining whether the paper unloading signal is output when the pickup roller carries out the pickup movement, and determining occurrence of a pickup error to stop the image forming apparatus when the paper unloading signal is not output. The apparatus and method sense the pickup error generated from inadequate movement of the pick-up roller without installing a separate paper sensor.

Abstract: Provided is an image forming apparatus. The image forming apparatus includes a print unit printing having a plurality of developer cartridges, each of which has a photoreceptor drum disposed therein. A plurality of fixing members are movable between a first position where the developer cartridges are installed and removed and a second position where the developer cartridges are fixed to the print unit. A pinion includes a female screw portion and a first sliding member includes a male screw portion that is engaged with the female screw portion, sliding backwards and forwards as the pinion rotates, and moving the fixing members to the first position or the second position.