Abstract: In a color image forming apparatus, the amount of light of an exposure unit for a weak exposure is changed according to a remaining service life of a photosensitive drum when the weak exposure is performed for the background area of a corresponding photosensitive drum by using the exposure unit.

Abstract: Provided are a multi-pass image forming apparatus and an image forming method using the same. The multi-pass image forming apparatus includes a plurality of developers for forming a plurality of electrostatic latent images using toners having different polarities and colors in one development process and for forming a multi-color image in at least two development processes; an exposure unit for forming the plurality of the electrostatic latent images on a photosensitive medium; and an intermediate transferring unit for having a toner images transferred thereon from the photosensitive medium that overlap to form the multi-color image, wherein the toner image may overlap another toner image on the intermediate transferring unit.

Abstract: A compact development apparatus using a two-component developer and an image forming apparatus wherein carrier deterioration is prevented to ensure formation of a high-quality image for a long time. The development apparatus uses the developer made up of a mixture of toner, carrier, and opposite polarity particles to be charged oppositely to the toner wherein the opposite polarity particles contain the particles having a relative dielectric constant of 6.7 or more.

Abstract: An electrophotographic image forming apparatus includes a photosensitive body, an exposing unit forming an electrostatic latent image on the photosensitive body subsequent to the photosensitive body being charged to a uniform electric potential, and a developing unit in which a toner composition having color toner constituents and transparent toner constituents are provided to develop the electrostatic latent image on the photosensitive body. The color toner constituents and the transparent toner constituents are charged to opposite polarities with respect to an intermediate potential.

Abstract: A developing apparatus including a developer container which contains a first developer having a first charging polarity and a second developer having a second charging polarity opposite to the first charging polarity, a developer bearing member which bears the first and the second developers, a layer forming device which forms a first layer substantially composed of the first developer on the developer bearing member and forms a second layer composed of the first and the second developers on the first layer, a separating member which is provided downstream of the layer forming device and upstream of a developing position in a developer bearing and conveying direction of the developer bearing member to separate the second layer from the developer bearing member, whereby plural kinds of developers can be selectively supplied for a development.

Abstract: In an electrophotographic apparatus, regions having at least three different potential levels Vc, Vw, and Vr are formed on a photosensitive member by using an exposing device, and developing processes respectively using colored particles of different kinds are performed by normal development and reversal development on two potential levels Vc and Vr excluding the intermediate potential level Vw. The apparatus has an auxiliary exposing unit for forming a fringe development preventing potential in an edge of an image forming region in order to prevent fringe development from occurring. The auxiliary exposing unit sets an auxiliary exposure amount by performing pulse-width modulation on a laser driver.

Abstract: In an image forming apparatus for charging a photosensitive body, changing the light exposure amount in at least three levels at exposure to light, thereby forming an electrostatic image made up of a high-potential part, a low-potential part, and an intermediate-potential part therebetween on the photosensitive body, and normally developing and inversely developing the electrostatic image using toners different in charge polarity for forming two types of toner images on the photosensitive body, a first developer used with a first toner image developing unit has electric resistance changed within 10% in the change range of applied voltage to the developer as the difference between a surface potential of the photosensitive body and a developing bias voltage.

Abstract: In an electrophotographic apparatus, regions having at least three different potential levels Vc, Vw, and Vr are formed on a photosensitive member by using an exposing device, and developing processes respectively using colored particles of different kinds are performed by normal development and reversal development on two potential levels Vc and Vr excluding the intermediate potential level Vw. The apparatus has an auxiliary exposing unit for forming a fringe development preventing potential in an edge of an image forming region in order to prevent fringe development from occurring. The auxiliary exposing unit sets an auxiliary exposure amount by performing pulse-width modulation on a laser driver.

Abstract: An electrophotographic color printer includes a photoconductor and a printing unit for producing a toner image on the photoconductor. The printing unit is removably provided in a receptacle in the printer.

Abstract: A method and apparatus for enhancing image resolution characteristics of an electrostatographic printing device use toners of opposite polarity to generate a toner image.

Abstract: A color electrophotographic printer that prepares a composite toner image for transfer by exposing an image area containing the composite toner image to an erase lamp and then running the composite toner image by an AC scorotron.

Abstract: An electrophotographic machine has a photoreceptive member supporting a composite color toner image formed of multiple layers of different colored toners. The composite toner image is pre-transfer charged at a first voltage level and recharge at a second voltage level less than the first voltage level. The background toner is preferentially charged by the second charging to reduce transfer of the background toner to the substrate.

Abstract: Full process color imaging is provided with the use of two xerocolography engines in tandem. Each of the two xerocolography engines is capable of creating three perfectly registered latent images with subsequent development thereof in a spot next to spot manner. Each engine is provided with three developer housing structures containing five different color toners including the three subtractive primary colors of yellow, cyan and magenta. Two of the primary colors plus black are used with one of the engines. The third primary color is used with the second tandem engine which also uses one of the primary colors used with the first engine as well as a fifth color which may be a logo or a gamut extending color. The full process color imaging capability provided is effected without any constraints regarding the capability of the laser imaging device to image through previously developed components of a composite image.

Abstract: A method for and apparatus for creating partial gamut color images in a single pass. A plurality of latent discharged area images are formed using a single exposure. A first discharged area image is developed followed by recharging of the photoreceptor containing the images. The images are then subjected to a partial erase step followed by the development of a second discharged area image. All images formed subsequent to the first discharged image except for the last image are preceded by recharging and partial erase to thereby optimize development and cleaning fields.

Abstract: An image forming method which forms a two color toner image or an image made up of two types of toners of the same color includes forming a first image with discharged area development (DAD) and a second image with charged area development (CAD). Resolution and sharpness of the first toner image is improved if the second toner image is formed by imagewise exposing a photoconductive member through a transparent base. Scavenging of the first toner image by the development of the second toner image and other aspects of the method are improved by use of a rotating magnetic core to drive a developer containing hard magnetic carrier in a soft brush through contact with the electrostatic image.

Abstract: The scavenging of a first toner into a second toning station in a DAD-CAD or CAD-DAD process can be reduced by allowing scavenged toner to deposit in the background of single color images. The polarity of the first toner of the scavenged toner is not changed prior to transfer and remains on the image member through transfer from which it is later cleaned. Alternatively, scavenged toner is deposited from a second toning station on the image member while no images are being made and allowed to pass through transfer to be cleaned off.

Abstract: An image-forming method using a latent-image forming body which consists of a transparent electrode layer, a photoconductive layer, an electrode layer and a pyroelectric-material layer made of a dielectric substance that are successively stacked on its transparent base. In this method, conductive carriers are generated in the photoconductive layer by irradiating information light thereto by using a light source that is placed at a location opposite to the transparent base. Then, heat is exerted at the light-irradiation portion of the photoconductive layer by applying a voltage across the transparent electrode layer and the electrode layer, and the heat causes a temperature rise in the pyroelectric-material layer such that an electrostatic latent image is formed by the pyroelectric effect. The electrostatic latent image is developed by allowing the developer, charged to have the polarity reversed to that of the electrostatic latent image, to be attracted by the electrostatic latent image.