Abstract: A mechanism and process for detecting mottle or banding in a developed electrophotographic image. Within an electrophotographic reproduction apparatus 10, a photoconductor is used for receiving and developing a latent image. The photoconductor traverses a path that passes a charging station 28, an exposure station 34, a toning station 38, and a transfer station 46. Either a densitometer 76 for measuring the density of the developed image on the photoconductor, or an electrometer 50a or 50b for detecting the voltage of the image on the photoconductor, detects mottle or banding on the developed image. The densitometer 76 or electrometer 50a or 50b has an aperture small enough to detect mottle or banding with wavelengths perceptible by human eyes.

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: A method and system for cleaning and removing particles from a printer machine quietly and efficiently with a variable speed blower whereby the blower can operate in a reduced power mode during normal operation and in an increased power mode for special cleaning operations in the printer machine.

Abstract: Development systems and methods for developing using magnetic toner are disclosed. The present invention further discloses developers used in development systems as well as the toner used in developer for magnetic ink character recognition printing. With respect to the development system, a development system is disclosed which includes a supply of dry developer mixture which contains magnetic toner particles and hard magnetic carrier particles. The development system further includes a non-magnetic, cylindrical shell for transporting the developer between the supply and the development zone, wherein the shell can be rotatable or stationary. A rotating magnetic core of a pre-selected magnetic field strength and means for rotating at least the magnetic core to provide for the transport of the toner particles from the shell to an electrostatic image also provided as part of the development system.

Abstract: A method and system for cleaning and removing particles from a printer machine quietly and efficiently with a variable speed blower whereby the blower can operate in a reduced power mode during normal operation and in an increased power mode for special cleaning operations in the printer machine.

Abstract: Disclosed are methods and apparatus for electrographic development which utilize a rotating magnetic core, a toner shell disposed around the rotating magnetic core, and developer compositions disposed on the toner shell which include a hard magnetic material, such as a strontium ferrite. The shell in embodiments has an outer surface with a surface roughness Ra of less than 32 microinches. The methods and apparatus do not require special manufacturing steps to place surface roughness or irregularities on the shell, and, thus, can provide the same or better image quality with relatively less complex manufacturing steps and at reduced cost.

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: An image forming apparatus uses an endless belt image member having a magnetic strip along one or more edges. A linear printhead is flashed in response to a magnetic encoder signal in the magnetic strip. Preferably, the apparatus has first and second linear writers and the magnetic encoding signal is created in the magnetic strip in conjunction with creation of a writing signal for the first writer with the second writer using the magnetic encoding signal to register its writing with the first writing. Preferably, an auxiliary signal is placed in the strip indicative of variable characteristics of either the image member or the image forming apparatus. This in turn is read by the apparatus and a charging, exposing or toning station controlled in response to the auxiliary signal.

Abstract: A development station for applying dry toner to an image member includes a rotatable magnetic core and an input skive to determine the height of the developer nap on a shell surrounding the core. Toner flakes showing up in the toner application on the image member are substantially reduced by replacing a previously metallic skive with a non-conductive skive to prevent heating of the skive from eddy currents created by the rotating core.

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 electrostatic image on an image member already containing a loose dry first toner image is toned with a second toner, for example, a toner of a second and different color from the first toner image. The toning is accomplished by a developer having a high coercivity permanently magnetized carrier and toner which is moved through a development zone by a rapidly rotating core inside a sleeve on which the developer moves. Pole transitions caused by the rapidly moving core make the high coercivity permanently magnetized carrier move vigorously in a wave motion having alternating crests and troughs. Scavenging of the first toner image is prevented by separating the sleeve from the image member sufficiently that the crests of the developer do not touch the image member during the toning process. An alternating electrical field is applied between the sleeve and the image member to enhance development.

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.

Abstract: An electrostatic image on an image member already containing a loose dry first toner image is toned with a second toner, for example, a toner of a second and different color from the first toner image. The toning is accomplished by a developer having a high coercivity permanently magnetized carrier and toner which is moved through a development zone by a rapidly rotating core inside a sleeve on which the developer moves. Pole transitions caused by the rapidly moving core make the high coercivity permanently magnetized carrier move vigorously in a wave motion having alternating crests and troughs. Scavenging of the first toner image is prevented by separating the sleeve from the image member sufficiently that the crests of the developer do not touch the image member during the toning process. An alternating electrical field is applied between the sleeve and the image member to enhance development.

Abstract: A process of forming a composite toner image, for example, a two color image, includes steps of charging and exposing an image member to create a first electrostatic image and developing the image to form a first toner image. The process is repeated to form two toner images on the same area or frame of an image member. To reduce the tendency of the first toner image to spread into the second electrostatic image and also to reduce scavenging of the first toner image by the second toning step, the image member is exposed, immediately after the formation of the first toner image, to uniform activating radiation to form charges of a polarity opposite the electrostatic image, which charges tend to hold the first toner image to the image member. The uniform exposure can be effected through a transparent support to the image member.

Abstract: A two component development system includes developer with charged toner particles and oppositely charged carrier particles having high coercivity and permanent magnetism. The developer is moved through a development zone on a shell and into contact with an image member carrying an electrostatic image by rapidly rotating a magnetic core within the shell. The core has alternating magnetic poles around its periphery. To prevent carryout of carrier on the image member, an AC bias is impressed across the development zone.

Abstract: A reproduction apparatus is provided including a development apparatus having a capability for precharging replenishment toner particles being added to a triboelectric charging sump containing partially depleted two-component developer material. The precharging capability of the development apparatus is provided by an AC bias and a first DC bias connected to a first toner particle metering member. A second DC bias is connected to a second metering member. The precharging capability of the present invention is particularly useful during development of images requiring large amounts of toner particles.

Abstract: An electrostatic latent image on a photoconductor of an electrophotographic device is developed by a gray scale monocomponent nonmagnetic development system using a combination of AC and DC bias voltages applied to a developer roller and a monocomponent nonmagnetic developer applied to the developer roller by an adder roller. The developer comprises a mixture of toner particles charged to one polarity and transparent beads charged to the opposite polarity, by triboelectric charging in bulk in an alternating field between the two rollers, rather than by friction contact with apparatus surfaces. The adder roller applies the charged mixture to the developer roller for developing the latent image in an electric field to an image density determined by the magnitude of the DC bias. A DC bias may be applied to the adder roller, especially to provide a gradient relative to the DC component of the developer roller bias for driving the bulk charged mixture onto the developer roller.