Pressure development apparatus for imaging sheets employing photosensitive microcapsules

Abstract

Methods and apparatus for pressure developing imaging sheets are described. In a three roll embodiment, first and second rolls are journaled into a housing to form a nip for rupturing microcapsules on the surface of an imaging sheet as it is passed through the nip. Such rolls are aligned at a slight skew angle and are resiliently pressed into one another by means of a third roll supported at a skew angle relative to the roll it contacts. In a two roll embodiment, the first and second rolls are crowned and pressed into contact with one another to present a uniform nip. In a four roll embodiment, the first and second rolls are aligned in parallel with each other, while a skewed roll backs up each of the first and second rolls. The backup rolls may alternatively be crowned. In any embodiment, the imaging sheet is directed into the nip to contact one roll at an angle of arc along the roll ahead of the nip. The nip may be defined partially open in the absence of a sheet, and the pressure rolls may be formed from hardened and chrome plated steel.

Dependencies are inferred from the claim text.