Roll seal blade support for a xerographic development unit using magnetic toner

摘要

In a xerographic development unit, particularly a unit for applying single-component magnetic toner such as used in MICR printing, the end of a donor roll which applies toner to the surface of a charge receptor is provided with a magnetic seal. The magnetic seal extends around at least a portion of the circumference of the roll, and defines a set of alternating magnetic poles arranged in bands which alternate along the length of the roll. The magnetic seal forms a uniform gap relative to the surface of the roll, the gap being sufficiently large to allow a turnover of toner particles therethrough. The design minimizes mechanical stresses on the toner, which in turn avoids the generation of frictional heat in the toner. A member defining magnetic poles can also be used as a shim for mounting a charge/metering blade within the development unit.