Wrap-limiting sheet cleaner for thin substrates

Abstract

A system for conveying sheets of thin substrate having low sheet stiffness while controlling and limiting the angle of wrap of the substrate on the roller, and a sheet cleaning apparatus employing the wrap-limiting system. A substrate conveyance roller is provided with a plurality of circumferential grooves spaced along the roller. Into each groove is disposed a substrate guide in near-tangential relationship with the surface of the roller at the point on the roller where stripping of the substrate from the roller surface is desired. In a preferred embodiment of a wrap-limiting system in accordance with the invention, one or more substrate guides are provided which extend through the grooves both upstream and downstream of the roller along the substrate conveyance path. The points at which the guide enters and leaves the groove define and limit the wrap angle assumable by the substrate on the roller. The invention is useful in conveying thin substrates on grooved conventional rollers as well as in cleaning thin substrates by contact cleaning rollers. A substrate cleaning system employing the invention includes first and second contact cleaning rollers, each preferably opposed by a backing roller, the substrate to be cleaned passing through the nip. Each CCR is provided with grooves and guides which are axially offset between the two rollers so that no portion of the substrate passes uncleaned.