Abstract: Apparatus and methods for electrographic image development, wherein the image development process is optimized by subjecting the developer to magnetic field maxima, thereby imparting to the developer a velocity component in a direction perpendicular to the process direction, ensuring that the toner particles thus accelerated have sufficient kinetic energy to overcome the binding energy binding the toner particles to the carrier particles in the developer, and to be deposited on a receiver bearing an electrostatic latent image. The optimized image is developed to completion, where development to completion is characterized by a proportionality between the cube of the toner charge to mass ratio and a quantity consisting of the magnitude of the voltage of the toning shell minus the magnitude of the voltage of the toned image.

Abstract: Compositions and methods for electrographic image development, wherein the image development process employs a two-component developer that includes toner particles having a radius RT and magnetic carrier particles having a radius RC, wherein RC is preferably less than about 5RT and is more preferably less than or equal to about 3RT.

Abstract: A method and apparatus for replenishing toner based on the electric current used over time by the exposure subsystem. Toner take-out for each image is estimated by measuring the current used by the exposure system, subtracting the quiescent current, integrating over a page or frame, and multiplying by a predetermined value that indicates the amount of toner required by the image, based on the average current used for the exposure and other process parameters. These calculations are done either in hardware or in software. The replenishment system is used to add the correct amount of toner to the developer station to maintain the toner concentration at an approximately constant aim value.

Abstract: Apparatus and methods for electrographic image development, wherein the image development process is optimized by subjecting the developer to magnetic field maxima, thereby imparting to the developer a velocity component in a direction perpendicular to the process direction, ensuring that the toner particles thus accelerated have sufficient kinetic energy to overcome the binding energy binding the toner particles to the carrier particles in the developer, and to be deposited on a receiver bearing an electrostatic latent image. The optimized image is developed to completion, where development to completion is characterized by a proportionality between the cube of the toner charge to mass ratio and a quantity consisting of the magnitude of the voltage of the toning shell minus the magnitude of the voltage of the toned image.

Abstract: A printer or other powder deposition device may include multiple toning stations, and the toning stations may be positioned in various configurations within the device. The various configurations may position the toning stations so as to increase the toning width of the device, thereby allowing the device to print larger process widths. The device may also perform processing control for the multiple toning stations.

Abstract: The invention relates generally to processes for electrostatic image development, and setpoints that provide uniform image development. In particular, an apparatus and process having a magnetic brush that implements a rotating magnetic core within a shell is disclosed. The process implements one or more of the following optimum setpoints: a range of shell surface speeds that provide uniform toning density, a range of shell surface speeds that prevent toner plate-out, a skive spacing that minimizes sensitivity to variation, a magnetic core speed that minimizes sensitivity to variation, and an imaging member spacing that minimizes sensitivity to variation.

Abstract: An electrographic machine 10 has a transfer station where a toner image is transferred to a receiver sheet 8. That sheet travels at a high speed of more than 15 inches per second and up to as high as 40 inches per second. A transfer roller has a metal core 212 and an elastomeric sleeve 214 with a resistivity selected to optimize transfer of toner at high speeds. The resistivity of the sleeve is selected to be high enough to support transfer of the toner but not so high as to cause the surface voltage to exceed the breakdown voltage of the dielectric material that includes the elastomeric sleeve, the receiver sheet, the toner and the photoreceptor.

Abstract: Apparatus and methods for electrographic image development, wherein the image development process is optimized by setting the average developer bulk flow velocity with reference to the imaging member velocity, for example, where the average developer bulk velocity is about the same as the imaging member velocity, or within preferred ranges, such as between about 40% to about 130% of the imaging member velocity.

Abstract: The invention relates generally to processes for electrostatic image development, and setpoints that provide uniform image development. In particular, an apparatus and process having a magnetic brush that implements a rotating magnetic core within a shell is disclosed. The process implements one or more of the following optimum setpoints: a range of shell surface speeds that provide uniform toning density, a range of shell surface speeds that prevent toner plate-out, a skive spacing that minimizes sensitivity to variation, a magnetic core speed that minimizes sensitivity to variation, and an imaging member spacing that minimizes sensitivity to variation.

Abstract: Compositions and methods for electrographic image development, wherein the image development process employs a two-component developer that includes toner particles having a radius RT and magnetic carrier particles having a radius RC, wherein RC is preferably less than about 5RT and is more preferably less than or equal to about 3RT.

Abstract: A system and method for increasing the rate at which the printing of images and documents can take place, is provided. The document or image to be reproduced is positioned at an image capture location. To capture the image, the desired image is illuminated by lamps and ultimately transferred onto paper. The illumination device is driven by multiple energy sources that can be synchronized to charge and fire in an alternating manner to drive the illumination device at the desired rate.

Abstract: The invention relates generally to processes for electrostatic image development, and setpoints that provide uniform image development. In particular, an apparatus and process having a magnetic brush that implements hard carriers and a rotating magnetic core within a shell is disclosed. The process implements one or more of the following optimum setpoints: a range of shell surface speeds that provide uniform toning density, a range of shell surface speeds that prevent toner plate-out, a skive spacing that minimizes sensitivity to variation, a magnetic core speed that minimizes sensitivity to variation, and an imaging member spacing that minimizes sensitivity to variation.

Abstract: A method and apparatus for replenishing toner based on the electric current used over time by the exposure subsystem. Toner take-out for each image is estimated by measuring the current used by the exposure system, subtracting the quiescent current, integrating over a page or frame, and multiplying by a predetermined value that indicates the amount of toner required by the image, based on the average current used for the exposure and other process parameters. These calculations are done either in hardware or in software. The replenishment system is used to add the correct amount of toner to the developer station to maintain the toner concentration at an approximately constant aim value.

Abstract: Apparatus and methods for electrographic image development, wherein the image development process is optimized by setting the developer mass flow velocity with reference to the imaging member velocity, for example, where the developer mass velocity is about the same as the imaging member velocity, or within preferred ranges, such as between about 40% to about 130% of the imaging member velocity.

Abstract: The invention relates generally to processes for electrostatic image development, and setpoints that provide uniform image development. In particular, an apparatus and process having a magnetic brush that implements hard carriers and a rotating magnetic core within a shell is disclosed. The process implements one or more of the following optimum setpoints: a range of shell surface speeds that provide uniform toning density, a range of shell surface speeds that prevent toner plate-out, a skive spacing that minimizes sensitivity to variation, a magnetic core speed that minimizes sensitivity to variation, and an imaging member spacing that minimizes sensitivity to variation.

Abstract: A composite toner image made up of first and second toners is formed on an image member. A first electrostatic image of a first polarity is formed on the image member. That electrostatic image is toned with a first toner of the first polarity. The image member is imagewise exposed to create a second electrostatic image also of the first polarity. Exposure is overlapped into the portion of the image member under the first toner image to prevent any charge on the photoconductor of the first polarity underneath the first toner image from repelling toner into the portions of the second electrostatic image that are discharged. Preferably, the second exposure is accomplished through the base of the image member in order to thoroughly expose portions of the electrostatic image underneath the first toner image.

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: Image forming apparatus forms first and second toner images in the same portion of an image member. To prevent scavenging of toner in the first image into a second toning station, lightly held toner in the first image is removed from the image member prior to the second toning station.

Abstract: A development station for toning electrostatic images includes a particle removing device positioned adjacent an applicator. A variable bias is applicable to the particle removing device for periodically removing carrier from the applicator for disposal. Carrier is periodically added to the station during replenishment of toner. The particle removing device can also be biased to remove toner instead of or in addition to removing carrier to control conditions of excess toner concentration.

Abstract: An image forming apparatus includes an image member which moves through a path past a series of stations. The series of stations create both first and second toner images on the same frame of the image member which images can be of different color. When the apparatus is used to form single color images, a charging station used in creating the second toner image is turned to a standby condition. In the standby condition, a bias is maintained on the charging station to repel toner particles from the first toner image that might otherwise accumulate on the charging station.