PLOTTING METHOD AND APPARATUS

摘要

A plotting system utilizing a drum plotter includes apparatus for steering a strip of recording paper or other recording material as the paper is fed back and forth by a plotting drum relative to a plotting head. The strip of paper is fed back and forth between two storage reels which are located at opposite sides of the plotting drum and the angular relationship of the storage reels relative to the plotting drum is controlled by servomotors to achieve steering of the paper as it passes over the drum. Between each of the storage reels and the plotting drum is a vacuum trough in which the strip of recording paper is accumulated to make paper immediately available during rapid movements of the plotting drum. The walls of the vacuum trough over which the paper is pulled have a waffled surface to reduce the area contacting the paper and the electrostatic charge build-up. The plotting head carries a slender shaft of consumable marking material, such as pencil lead or graphite, which is capable of producing uniform line intensity at any plotting speed as long as a light stylus pressure is applied to the shaft. By plotting a mirror image of a desired graphic display with a lead containing a dye, it is possible to produce a master from which duplicate copies of the graphic display can be printed in a conventional dye transfer process.