Patent ID: 7281779

Claim:
A method for measuring the length change of a feed spindle in an exposer for recording printing originals, which comprises: fixing a recording material to an exposure drum; providing an exposure head carrier with at least one exposure head adapted to focus exposure beams; axially moving the exposure head carrier along the exposure drum in a feed direction with a stepping motor of a feed drive and the feed spindle to carry the at least one exposure head and focus the exposure beams onto the recording material, the stepping motor moving in stepping motor cycles; during a basic setting of the feed drive, setting an optimum number K 0 of the stepping motor cycles per revolution of the exposure drum and determining a number M 0 of the stepping motor cycles needed by the exposure head carrier to travel through a reference section substantially parallel to the feed direction; and immediately before recording a printing original, determining a number M x of the stepping motor cycles needed by the exposure head carrier to travel through the reference section.