Apparatus for wet treatment of webs of photosensitive material

Abstract

A tank for wet treatment of a running web of photosensitive material has a set of upper pulleys and a set of lower pulleys mounted on a common support and movable up and down toward and away from the upper pulleys. The web is alternatingly trained over the upper and lower pulleys to advance along a meandering portion of its path from a first drive at the inlet into the body of liquid in the tank to a computer-controlled second drive at the locus of emergence of the web from the body of liquid. At least one additional drive is provided for one or more median upper pulleys to thus reduce the tensional stress upon the repeatedly looped running web. The additional drive can employ a capacitor motor, a d-c motor, a hysteresis motor or clutch, a pneumatic motor or a hydraulic motor. Such additional drive can rotate the respective upper pulley at a constant speed or at a speed which varies as a function of changes in the speed of advancement of the web through the body of liquid. The web is tensioned solely by the weight of the lower pulleys and of the common support for the lower pulleys.

Dependencies are inferred from the claim text.