Abstract: Apparatus and an associated method for ascertaining the operational status of a pen in a vector plotter in which a pen is moved into contact with a paper web at a test location, the pen is moved relative to the web and an optical detector is used to determine whether or not the pen is drawing a line on the web. The web is moved from a supply roll to a take-up roll to move the test area on the web to an optical testing location. The absence of a line after a pre-determined period of web movement time signals the inoperative status of the pen and the detection of a line by the pen within that pre-determined period of movement time signals that the pen is operative. Quality and proper line width of the line can also be determined.

Abstract: A multicolor electrostatic plotter is disclosed and includes an image head for imparting a charge pattern to a web medium to be imprinted and a plurality of toner means associated with different colors in which different colors are successively applied to portions of the medium by repeatedly driving and rewinding a portion of the medium past the image head and the plurality of toner means for charge and toner application to imprint multiple color rasterized images on the medium by the use of electronic circuitry which imprints a reference track on the medium during the first color pass and then optoelectronically detects deviations, generally perpendicular to the directional movement of the medium, of the medium during successive color passes substantially instantaneously with the deviations and which electronically adjusts the input data from a remote rasterizer by an amount equal to the substantially instantaneous offset so that lines of raster data are shifted by an amount substantially equal to the instan