Samsung Electronics Co., Ltd.

Su-jong Jeong

Ui-Choon Lee

Byoung-chul Bae

Dyoung-chul Bae

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. The apparatus also includes a charging roller resistance detection unit detecting a resistance value of the charging roller, a transfer roller resistance detection unit detecting a resistance value of the transfer roller, and a control unit determining the charging voltage to be applied to the charging roller based on the charging roller resistance value detected by the charging roller resistance detection unit and the transfer roller resistance value detected by the transfer roller resistance detection unit. Accordingly, the present invention can adaptively select a charging voltage to be applied to the charging roller depending upon the changes of the transfer roller resistance value and the charging roller resistance value.

Electrophotographic image-forming apparatus and charging voltage control method thereof

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.

Image forming apparatus including a subsidiary transfer part having a fiber optic guide

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.

Method of detecting lifespan of transfer roller and electrophotographic image forming apparatus employing the method

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.

Charging voltage controller of image forming apparatus

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.

Method and apparatus for an electrophotographic printer where voltage magnitude applied to charge roller and intensity of illumination unit vary depending on type of print job submitted

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.

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Suwon, South Korea

Su-jong Jeong