Toner applicator system for magnetography

Abstract

In a high-quality, high-speed magnetographic apparatus, an arrangement for developing the latent magnetic images of a readily-imagable magnetizable medium (in particular a relatively high-coercivity medium) with magnetically attractable toner particles. A rotatable toner developer is positioned proximate to the medium to define therebetween a toning zone, with the developer being structured to magnetically provide toner particles in contact with the medium at the toning zone and to impart to the toner particles at least at and approaching the toning zone a direction of movement relative to the medium which is in opposition to the latter. A concentration of substantially fluidized and magnetically confined toner particles is thus provided which is urged into contact with the medium for effectively developing the latent images even with the medium moving at high speed relative to the developer and without adversely affecting the latent magnetic images of the medium. A magnetic field enhancer is positioned proximate to the toning zone on the opposite side of the magnetic medium from the developer, which effectively enhances the shape of the magnetic field at the toning zone in the general direction toward the magnetic medium thereby increasing the magnetically generated toner contact pressure. A scavenger arrangement is included for collecting any air-borne toner, for removing excess toner residing on the developed image areas of the medium, and for removing stray toner particles residing on the non-imaged areas and the back of the medium. The continuity of toning provided to the medium is facilitated by an eccentrically operated toner rake arrangement situated in the toner bin for urging the toner particles in the toner bin toward the developer. Alternatively, the toner can be rendered fluidized by a oscillating floor or wall arrangement resiliently coupled to the remainder of the toner bin. The developer is provided with a channel arrangement governing the approach of the toner particles thereto which are received from the action of say the toner rake. The channel arrangement ensures that the toner is introduced to the developer in a well defined narrow band the width dimension of which is commensurate with the width of the desired imaged portion of the magnetic medium. The developer station is particularly effective in both a substantially horizontal orientation, underneath the magnetic medium, and at a substantially vertical angle and proximate to the outside surface of the medium.