Abstract: An electrophotographic image forming apparatus includes first and second photosensitive bodies, first and second exposing units to form electrostatic latent images on the first and second photosensitive bodies each of which being charged to a uniform electric potential, a first developing unit to develop the electrostatic latent image on the first photosensitive body by supplying a transparent toner thereto, and a second developing unit to develop the electrostatic latent image on the second photosensitive body by supplying color toners thereto, wherein the first developing unit is a developing unit employing a two-component developing technique using a magnetic carrier and a transparent toner.

Abstract: An image forming apparatus and method for controlling a charge of a toner are provided. The apparatus and method includes a toner supplying roller; a developing roller for supplying the toner to an organic photoconductor; a charge controller for adjusting the charge of the toner on the developing roller; a developing current detector for detecting a change in current for a developing voltage; and a charge controlling voltage controller for adjusting a charge controlling voltage according to the detection result. The apparatus can uniformly maintain the quality of an image by recognizing a change in the charge of toner based on a change in the environment. Also, the image forming apparatus indicates a proper toner replacement time by determining when the charge of the toner is abnormally low as a toner shortage state and displaying the toner shortage state on a panel operating unit.

Abstract: A hybrid development apparatus and a development method therefor are provided. The hybrid development apparatus includes a magnetic roller, a donor roller, and a collecting roller. A supply bias voltage, a development bias voltage, and a collecting bias voltage are respectively applied to the three rollers. The three bias voltages are tri-level bias voltages having same voltage duties of maximum, medium and minimum voltages and phases thereof are different by 120 degrees from each other.

Abstract: A developer for an electrophotographic image forming apparatus including a toner charging roller is provided. The developer includes: a developing roller which faces a photosensitive medium and rotates to transfer toner to the photosensitive medium to develop the electrostatic latent image on the photosensitive medium; a supply roller which faces the developing roller and rotates to supply the toner to the developing roller; a regulating blade which is provided at one side of the developing roller and regulates the toner supplied onto the surface of the developing roller to have a uniform thickness, and triboelectrically charges the toner; and a toner charging roller which faces the developing roller and rotates to triboelectrically charge the toner between the supply roller and the regulating blade.

Abstract: An electro-photographic image forming apparatus preventing toner from scattering during a printing operation and a control method of the same. The electro-photographic image forming apparatus includes a scattering preventive member being disposed downstream of the developing roller at a predetermined distance from the photosensitive medium, and a voltage being applied, and a controller controlling the voltage that is applied to the scattering preventive member so as to transport the toner attached on the scattering preventive member to the photosensitive medium.

Abstract: A developing device having a developing gap detecting function includes a photosensitive medium, a developer conveyer, a DC power source, an AC power source, a current detecting unit and a controller. The current detecting unit detects a DC current flowing on the developer conveyer when toner from the developer conveyer is attached to a desired area of an electrostatic latent image on a photosensitive body by enhancing a voltage outputted from a power supply gradually at proper intervals. The controller obtains a developing gap between the photosensitive medium and the developer conveyer based on current values detected by the current detecting unit. In accordance with the developing device having the developing gap detecting function, the developing gap is sensed and developing voltage is easily and correctly calculated to control image forming conditions. As a result, an image quality improves.

Abstract: An image forming apparatus and method for controlling a charge of a toner are provided. The apparatus and method includes a toner supplying roller; a developing roller for supplying the toner to an organic photoconductor; a charge controller for adjusting the charge of the toner on the developing roller; a developing current detector for detecting a change in current for a developing voltage; and a charge controlling voltage controller for adjusting a charge controlling voltage according to the detection result. The apparatus can uniformly maintain the quality of an image by recognizing a change in the charge of toner based on a change in the environment. Also, the image forming apparatus indicates a proper toner replacement time by determining when the charge of the toner is abnormally low as a toner shortage state and displaying the toner shortage state on a panel operating unit.

Abstract: An electro-photographic image forming apparatus preventing toner from scattering during a printing operation and a control method of the same. The electro-photographic image forming apparatus includes a scattering preventive member being disposed downstream of the developing roller at a predetermined distance from the photosensitive medium, and a voltage being applied, and a controller controlling the voltage that is applied to the scattering preventive member so as to transport the toner attached on the scattering preventive member to the photosensitive medium.

Abstract: A toner layer regulating member and a developing device using the toner layer regulating member. The toner layer regulating member forms a uniform toner layer on a toner transfer unit, electrically charges a toner by friction, and includes a polyolefin-based elastic rubber member which contacts the outer circumference surface of the toner transfer unit and whose surface is ultraviolet-treated. Thus, a uniform toner layer can be formed on the toner transfer unit and the toner is electrically charged by friction. As a result, a high quality image having no defects can be provided.

Abstract: A developing device having a developing gap detecting function includes a photosensitive medium, a developer conveyer, a DC power source, an AC power source, a current detecting unit and a controller. The current detecting unit detects a DC current flowing on the developer conveyer when toner from the developer conveyer is attached to a desired area of an electrostatic latent image on a photosensitive body by enhancing a voltage outputted from a power supply gradually at proper intervals. The controller obtains a developing gap between the photosensitive medium and the developer conveyer based on current values detected by the current detecting unit. In accordance with the developing device having the developing gap detecting function, the developing gap is sensed easily and correctly by perceiving a discharge start voltage, and image forming conditions are controlled, thereby improving an image quality.

Abstract: A toner layer regulating member and a developing device using the toner layer regulating member. The toner layer regulating member forms a uniform toner layer on a toner transfer unit, electrically charges a toner by friction, and includes a polyolefin-based elastic rubber member which contacts the outer circumference surface of the toner transfer unit and whose surface is ultraviolet-treated. Thus, a uniform toner layer can be formed on the toner transfer unit and the toner is electrically charged by friction. As a result, a high quality image having no defects can be provided.

Abstract: A developing roller installed in an image forming apparatus to transfer a toner to a photosensitive member and a manufacturing method of the developing roller include a roller member having an outer cylindrical vessel, an inner vessel installed within the outer cylindrical vessel in concentric with the outer cylindrical vessel, a hollow portion formed at a center of the inner vessel, and a plurality of ribs connecting and supporting the outer cylindrical vessel and the inner vessel so as to connect and support the outer cylindrical vessel and the inner vessel, and a rotating shaft compressively fitted into the hollow portion of the inner vessel.

Abstract: A method for achieving adjusted toner concentration of printed image on a recording medium in an image forming apparatus using an electrophotographic developing process including a photosensitive drum for forming a latent image on its negatively charged photoconductive insulating surface exposed to light according to an image pattern and a developing roller charged with a negative developing voltage to charge by rubbing a toner supplied from a toner supplier with a negative voltage.

Abstract: A method of automatically controlling an electrophotographic printing apparatus' transfer voltage and fusing temperature according to the type of paper by an automatic mode change during manual paper feeding which includes the steps of following a manual feed option being selected, automatically converting the apparatus's normal paper mode into a paper selection mode in response to the manual paper feeding; and when a keyboard input is made indicating a change in the type of paper, setting the transferring voltage and fusing temperature according to the keyboard input and printing images corresponding to image data from a host computer system on the paper.