Fluid supported belt about cylindrical mandrel for transporting magnetic particles

In apparatus for transporting finely divided magnetic particles from a bulk source for delivery to a transfer region in a uniformly dispersed layer, the combination of:

• fixed, non-magnetic mandrel structure of generally cylindrical shape, said structure including a cavity extending transversely of the central axis thereof;
• a plurality of evenly circumferentially spaced lands extending longitudinally of the surface of said mandrel structure;
• means defining radially presented fluid discharge orifices in each of said lands;
• means defining cavities in said mandrel structure for feeding fluid under pressure to said orifices for discharge therefrom;
• a relatively thin, cylindrically formed magnetic particle transporting belt disposed coaxially about said mandrel structure;
• bearing means supporting said belt for rotation about said mandrel structure;
• magnet means disposed within said transversely extending cavity in said mandrel and including magnetic flux-concentrating pole pieces disposed in close proximity to said belt and extending parallel to the axis thereof;
• and means for driving said belt on said bearing means.

Fluidically supported ink transporting belt means for use in printing apparatus of the type utilizing dry magnetic ink as the recording medium, comprising:

• means defining a generally cylindrical mandrel having fluid supply cavities and a magnet support cavity;
• a thin flexible cylindrically formed weakly magnetic metallic belt disposed coaxially with and closely spaced about said mandrel;
• means supporting said belt in substantially fluid tight relation along opposed edge regions thereof and affording rotation of said belt about said mandrel;
• means defining radially presented orifices in said mandrel and communicating with said fluid supply cavities and with the relatively close space provided between said belt and said mandrel;
• a magnet in said magnet cavity having pole pieces so shaped and disposed as to maintain a magnetic field parallel to the axis of and extending transversely across the surface of the cylindrically formed belt;
• means for rotating said belt about said mandrel;
• means for dispersing dry magnetic ink over the surface of said belt;
• and means for introducing fluid under pressure into said fluid supply cavities for flow through said orifices into the recited space, said fluid being effective substantially to pressurize said space and rigidify said belt as it rotates, said magnetic field being effective to form and maintain a non-translating, elongate rotating pencil like rotating ink bead on the surface of said belt as it rotates.