Film cassete spool with exposure indicator

摘要

A film spool of the type which is rotatable inside a light-tight cassette shell as a film strip coiled about the spool is pulled out of the shell, has a film exposure status indicator movable from a first position to a second position where it provides a visible indication that the film is completely exposed. The status indicator includes an element movable within the hollow interior of the spool core between the first and second positions, a spring urging the element towards the second position, and a retaining device cooperating with an end portion of the film strip to prevent movement of the element until the film strip has been fully unwound.