Abstract: An erase unit for an ion deposition web-fed print engine includes a plenum extending the width of the electrostatic image on the image cylinder and defining an ionization chamber with the image cylinder surface. The plenum has first and second electrodes separated by a dielectric. Upon application of a time-varying potential having a frequency of 0.2 to 50 mHz across the electrodes, ionization occurs, causing an ion current flowing in relation to the image surface until the image surface and the biasing electrode are at the same potential, thus erasing any residual electrostatic image on the cylindrical surface. By providing a DC biasing voltage, the residual electrostatic image may be erased when equalization occurs, with the image cylinder maintaining a pre-charged potential.

Abstract: A system for the delivery of a substantially uniform mono-layer of toner to an electrostatic latent image in an imaging member (such as a rotating cylinder) insures proper handling of the toner, and utilizes first and second rollers which function as a polarity filter for toner, allowing only particular charged toner to be transferred from a toner reservoir to the imaging member. The twin roller delivery system comprises first and second rollers mounted for rotation about substantially parallel substantially horizontal axes, so that the peripheral surface of the first roller receives the toner from the substantially open top reservoir, and the second roller receives toner from the first roller and transfers it to the imaging member. The first and second rollers are charged to different electrical potentials, e.g. both being positive with the second roller at a potential that is about 400 volts below the first. The rollers are rotated in opposite directions about the axes of rotation.

Abstract: A toner composition for developing an electrostatic latent image comprising a base toner, which is a blend of a polymeric resin and a colorant, and one or more of a lubricating agent, a flowability agent, a charge-stabilizing agent, and a conductive agent, which has certain electrical characteristics. The base toner has a mean particle diameter (D.sub.50) of 7 to 18 microns, and a bulk resistivity of greater than 10.sup.12 ohm-cm. The toner composition is prepared by blending a polymeric resin with a colorant and then blending a dry powder lubricating agent, and optionally other additives, with the base toner. The toner composition is charged by being disposed in an electrostatic fluidized bed from which the toner particles are levitated by air and then subjected to field charging created by a high voltage corona generating device contained within the bed.

Abstract: Electrically conductive magnetic toner is supplied to an electrostatic printing apparatus by dispensing it pneumatically from one of two different toner bottles mounted on dispenser blocks. The toner passes through a chute into a container having an air previous, toner impervious, bottom. The toner particles are fluidized in the container, and come into contact with the rotating surface of an applicator roller having interior magnets, and the amount of toner which stays on the applicator roller surface is controlled in part by rotating the surface past a metering blade. To periodically declump the toner, a mechanical element is depressed which reverses the direction of the applicator roller, and brings a scraper blade into contact with the surface of the applicator roller, and applies a high level of vacuum to remove scraped off toner.

Abstract: Charged toner is transferred from an image member (such as an image cylinder or belt) to a web of imagable material (typically paper), preferably utilizing a rotating conductive impression cylinder. The toner, having a first polarity, is applied to the image member. The paper web, typically by contact with the impression cylinder, is moved into contact with the image member so that the toner transfers from the image member to the web under pressure. Even despite a high speed of movement of the web (e.g. 200 feet per minute or more), toner back scatter is substantially prevented by applying an electrical bias of the first polarity to the impression cylinder so as to impose an electric force field on the toner particles of sufficient intensity to overcome aerodynamic drag forces which would separate particles from the image areas between the impression cylinder and the image member.