Abstract: A display device includes: a first pixel electrode disposed in a first emission area, on a substrate; an insulating layer covering edges of the first pixel electrode; a first light-emitting layer disposed on the first pixel electrode and the insulating layer; a first common electrode disposed on the first light-emitting layer; banks disposed on the insulating layer and surrounding the first emission area; and a first organic pattern surrounding the first emission area, disposed on the banks, and including the same material as the first light-emitting layer. Side surfaces of each of the banks are spaced apart from side surfaces of the insulating layer.

Abstract: An electrophotographic image-forming apparatus and a charging voltage control method therefor. The electrophotographic image-forming apparatus has a charging roller applying a predetermined voltage to a photosensitive medium, a developing roller for developing with a developing agent an electrostatic latent image formed on the photosensitive medium by a laser scanning unit, a transfer roller transferring onto a sheet of recording paper the image developed by the developing agent, and a high voltage power supply (HVPS) applying predefined voltages to the respective rollers.

Abstract: An image forming apparatus includes a developing device having a photosensitive element rotating in a given direction to form a latent electrostatic image on a surface thereof through a laser scanning unit, and a developing roller developing the latent electrostatic image into a toner image using a developer, a transfer part transferring the toner image onto a transported printing paper disposed on a paper-transporting path to engage the photosensitive element, and a subsidiary transfer part having at least one light source disposed on at least one of both sides of the paper-transporting path to expose the photosensitive element to light and thereby to enhance a transfer efficiency, and an optic fiber guide disposed longitudinally along the photosensitive element to lead the light generated from the light source to the photosensitive element.

Abstract: An electrophotographic image forming apparatus and method. The apparatus has a laser scanning unit to generate a laser beam, a photosensitive medium to receive the laser beam and form an electrostatic latent image, a developing roller to attach toner to a surface of the photosensitive medium, a transfer roller to transfer the developed image onto a paper sheet, a charge roller to charge the surface of the photosensitive medium to have a predetermined voltage, a power supply to supply electric power to the transfer roller and the charge roller, a transfer roller resistance detecting unit to detect a resistance of the charge roller, an actual surrounding condition detecting unit to detect an actual surrounding condition of the charge roller, and a controller to detect a surrounding condition from the resistance of the charge roller, compare the detected surrounding condition with the actual surrounding condition, and generate a transfer roller exchange signal if the two surrounding conditions differ.

Abstract: A charging voltage controller of an image forming apparatus includes a charging roller charging a photoconductive drum with a predetermined charging voltage, a high voltage supply unit supplying the predetermined charging voltage to the charging roller, an electric current detecting unit detecting an electrical current flowing the charging roller, and a control unit supplying first and second test voltages of different degrees to the charging roller, determining a first reference voltage to be applied to the charging roller based on data from the electric]current detecting unit outputted in response to the first test voltage, calculating slope data based on the electrical current data detected from the electric current detecting unit in response to the first and second test voltages, and determining the charging voltage to be applied to the charging roller as a sum of the first reference voltage and a preset offset voltage that corresponds to the slope data.

Abstract: An electrophotographic printing method and apparatus in which a charge voltage is appropriately adjusted depending on the resolution selected for electrophotographic printing or the print mode are provided. The electrophotographic printing method and electrophotographic imaging apparatus provide for selecting a resolution for electrophotographic printing; charging an organic photoconductor (OPC) by applying to a charge roller an appropriate charge voltage depending on the selected resolution; forming an electrostatic latent image on the charged OPC by a laser scanning unit (LSU) and applying toner particles adhering to a developer roller to the electrostatic latent image to form a visible image; and transferring the visible image formed on the OPC to a sheet of print paper. By selecting the print resolution or print mode, the charge voltage can be adjusted depending on the print resolution or print mode, so that an image can be obtained with reduced image concentration variation.

Abstract: An electrophotographic image-forming apparatus and a charging voltage control method therefor. The electrophotographic image-forming apparatus has a charging roller applying a predetermined voltage to a photosensitive medium, a developing roller for developing with a developing agent an electrostatic latent image formed on the photosensitive medium by a laser scanning unit, a transfer roller transferring onto a sheet of recording paper the image developed by the developing agent, and a high voltage power supply (HVPS) applying predefined voltages to the respective rollers.

Abstract: An electrophotographic image forming apparatus and method. The apparatus has a laser scanning unit to generate a laser beam, a photosensitive medium to receive the laser beam and form an electrostatic latent image, a developing roller to attach toner to a surface of the photosensitive medium, a transfer roller to transfer the developed image onto a paper sheet, a charge roller to charge the surface of the photosensitive medium to have a predetermined voltage, a power supply to supply electric power to the transfer roller and the charge roller, a transfer roller resistance detecting unit to detect a resistance of the charge roller, an actual surrounding condition detecting unit to detect an actual surrounding condition of the charge roller, and a controller to detect a surrounding condition from the resistance of the charge roller, compare the detected surrounding condition with the actual surrounding condition, and generate a transfer roller exchange signal if the two surrounding conditions differ.

Abstract: An image forming apparatus compensating for printing density of a toner image by adjusting a quantity of light to form the toner image in accordance with a variation of a resistance of a roller includes an electrical charge roller electrically charging a photosensitive drum, a laser scan unit projecting the image light on the photosensitive drum to form an electrostatic latent image corresponding to an input image, a development roller developing the electrostatic latent image formed on the photosensitive drum with toner to form the toner image, a transfer roller rotating in contact with the photosensitive drum and transferring the toner image to a sheet of paper when a predetermined voltage is supplied to the transfer roller, and a controller controlling the laser scan unit and varying the quantity of the image light projected from the laser scan unit in accordance with the variation of a resistance value of the transfer roller.

Abstract: A charging voltage controller of an image forming apparatus includes a charging roller charging a photoconductive drum with a predetermined charging voltage, a high voltage supply unit supplying the predetermined charging voltage to the charging roller, an electric current detecting unit detecting an electrical current flowing the charging roller, and a control unit supplying first and second test voltages of different degrees to the charging roller, determining a first reference voltage to be applied to the charging roller based on data from the electric]current detecting unit outputted in response to the first test voltage, calculating slope data based on the electrical current data detected from the electric current detecting unit in response to the first and second test voltages, and determining the charging voltage to be applied to the charging roller as a sum of the first reference voltage and a preset offset voltage that corresponds to the slope data.

Abstract: An image forming apparatus includes a developing device having a photosensitive element rotating in a given direction to form a latent electrostatic image on a surface thereof through a laser scanning unit, and a developing roller developing the latent electrostatic image into a toner image using a developer, a transfer part transferring the toner image onto a transported printing paper disposed on a paper-transporting path to engage the photosensitive element, and a subsidiary transfer part having at least one light source disposed on at least one of both sides of the paper-transporting path to expose the photosensitive element to light and thereby to enhance a transfer efficiency, and an optic fiber guide disposed longitudinally along the photosensitive element to lead the light generated from the light source to the photosensitive element. The apparatus may include an erasing part having the same structure as that of the subsidiary transfer part.

Abstract: An image forming apparatus compensating for printing density of a toner image by adjusting a quantity of image light to form the toner image in accordance with a variation of a resistance of a roller includes an electrical charge roller electrically charging a photosensitive drum, a laser scan unit projecting the image light on the photosensitive drum to form an electrostatic latent image corresponding to an input image, a development roller developing the electrostatic latent image formed on the photosensitive drum with toner to form the toner image, a transfer roller rotating in contact with the photosensitive drum and transferring the toner image to a sheet of printing paper when a predetermined voltage is supplied to the transfer roller, and a controller controlling the laser scan unit and varying the quantity of the image light projected from the laser scan unit in accordance with the variation of a resistance value of the transfer roller.

Abstract: An electrophotographic printing method and apparatus in which a charge voltage is appropriately adjusted depending on the resolution selected for electrophotographic printing or the print mode are provided. The electrophotographic printing method and electrophotographic imaging apparatus provide for selecting a resolution for electrophotographic printing; charging an organic photoconductor (OPC) by applying to a charge roller an appropriate charge voltage depending on the selected resolution; forming an electrostatic latent image on the charged OPC by a laser scanning unit (LSU) and applying toner particles adhering to a developer roller to the electrostatic latent image to form a visible image; and transferring the visible image formed on the OPC to a sheet of print paper. By selecting the print resolution or print mode, the charge voltage can be adjusted depending on the print resolution or print mode, so that an image can be obtained with reduced image concentration variation.

Abstract: Disclosed is an electronic photograph forming apparatus including a supplying roller, a developing roller, a charging roller, a laser scanning unit (LSU), a transferring roller, an organic photoconductive (OPC) drum, a pre-transfer lamp (PTL), a controller, and a power supply. The organic photoconductive drum is charged by the charging roller. An electrostatic latent image is formed on the organic photoconductive drum by the laser scanning unit, and the electrostatic latent image is changed into a visible image by toner supplied from the developing roller. The pre-transfer lamp reduces the attached force of toner attached to the organic photoconductive drum to a predetermined level. The controller varies the voltage of the transferring roller according to a predetermined standard so that toner remaining on the transferring roller is transferred to the organic photoconductive drum while the organic photoconductive drum and the transferring roller are raced.

Abstract: A method of and apparatus for controlling a transfer voltage based on a paper specific resistance in a laser beam printer is provided. In the transfer voltage controlling method, the resistance of the feed rollers is detected as a first resistance before a paper sheet passes between the feed rollers. The resistance of the paper sheet and the feed rollers is detected as a second resistance when the paper sheet passes between the feed rollers. The specific resistance of the paper sheet is obtained as a third resistance by determining the difference between the first resistance and the second resistance. The resistance between a transfer roller and a photosensitive drum is detected as a fourth resistance before the paper sheet passes through the transfer roller. A composite resistance is detected as a fifth resistance by adding the third resistance to the fourth resistance, and the paper sheet is printed by applying a transfer voltage to the transfer roller based on the fifth resistance.

Abstract: An image forming apparatus reads a composite resistance of an OPC drum and a transfer roller before a sheet of recording paper has advanced between the OPC drum and the transfer roller to provide a proper transfer voltage. To this end, the apparatus provides a first transfer voltage to the transfer roller to detect a composite resistance between the OPC drum and the transfer roller, before the recording paper has advanced between the OPC drum and the transfer roller. When the leading edge of the recording paper has arrived between the OPC drum and the transfer roller, the apparatus provides the transfer roller with a second transfer voltage in accordance with the detected composite resistance. Further, a composite resistance of the OPC drum, the transfer roller and the recording paper is detected after the second transfer voltage is supplied to the transfer roller.

Abstract: An engine unit for an image forming apparatus transfers a toner image without corona discharge by adjusting a quantity of light radiated from pre-transfer lamps (PTLs). In the engine unit, a charge roller forms a uniform charge on an organic photoconductive (OPC) drum, and an exposure unit exposes the OPC drum to a light beam to form an electrostatic latent image. The PTLs apply a predetermined intensity of light to a non-image area on the OPC drum to change a potential of the non-image area to a value similar to a potential of an image area on the OPC drum, by adjusting a resistance value of resistors connected to the PTLs, so as to prevent a toner from remaining at a border between the image area and the non-image area. A transfer roller transfers the toner attached to the OPC drum to a recording sheet.