Alternately engageable, dual-stage cleaning system for lithographic

Abstract

Cleaning apparatus for lithographic printing plates includes a rotating elastomeric roller that contacts imaged plates, which are typically (although not necessarily) carried on a rotary cylinder, at a velocity different from the velocity (if any) of the plate. The roller may spin in the direction of, or opposite to, that of the cylinder and at substantially different speed. Typically, the apparatus is mounted proximate to the cylinder, circumferentially adjacent to the imaging system, and is retractable so as to be selectively engaged when imaging is complete. The apparatus may include, in addition to or in lieu of the elastomeric roller, a second retractable cleaning member for rubbing the imaged plate with a cleaning fluid. The second cleaning member may be an elongated cartridge having an absorbent towel exposed along one face thereof. A cleaning fluid is dispensed onto the towel by, for example, a spraying device. The cartridge is then extended to urge the towel against the printing plate as it rotates.