Abstract

A graduated, highly tensioned metallic codestrip is used in a large-format automatic image-related device such as a D-size or larger plotter, yielding positional precision even better than those of prior small-format devices. Preferably perforations in the strip are the graduations, used in determining position of a carriage that holds image transducers (e. g., pens). The strip passes through a slot (open along one edge, closed at the other) in a perforation sensor. The image transducers are very close to the slotted sensor and the strip, to minimize the effect of disturbances arising between the strip and transducers. Two unperforated portions of the strip--one relatively broad, and another relatively narrow border portion--provide very good structural stability for the tensioned strip. Stability under tension is enhanced by wrapping the strip partway around a stanchion at each end. The perforations are formed between the two unperforated portions at a periodicity of one hundred fifty orifices or more per inch, defining position within one three-hundredth of an inch or better. Preferably the strip is oriented with the narrow border nearer the closed edge of the sensor slot. In a multielement marking-device system the novel strip yields fine coordination for marks in adjacent swaths or by plural pens. It also helps meet stringent demands of bidirectional marking.