Abstract: The invention disclosed herein provides a method and apparatus for counteracting the effects of a localized drag on a sheet medium as it is being moved by a drive system, for example, in a printer or plotter to prevent misregistration of the sheet medium with the X-axis drive system as the sheet medium is moved past the print or plot head which creates a drag thereon. The sheet medium is stiffened in the region thereof which is contacted by the print or plot head by bending the sheet medium in a direction normal to the direction of movement of the sheet medium. The bend may be provided by a curved guide located between the print or plot head and the X-axis drive system. Friction is reduced between the sheet medium and the curved guide by mounting the curved guide, e.g., one or more rollers, to rotate freely under the action of the sheet medium moving thereover, or by pneumatically supporting the sheet medium above the curved guide as the sheet medium is moved thereover.

Abstract: Apparatus especially X-Y plotters having a marking device for marking a surface. A support is provided for supporting the marking device. The support is movable along an axis of the housing while the marking device can be selectively raised and lowered relative to the surface. The raising and lowering is carried out by means of a flexible driving element, for example, a cable, connected to a pivotable link on the support and activated by a motor. The marking device support is freely translatable relative to the flexible driving element.

Abstract: Apparatus is disclosed for use with printers (or plotters) for storing and transferring ink-containing ribbon cassettes between a print head and a storage location. The printers (or plotters) are of the type which include a print head that is not as wide as the width of the medium to be printed on so that the print head has to be moved to print (or plot) across the full width of the medium. The apparatus automatically removes a cassette mounted to the movable carriage to which the print head is also mounted and deposits it in the storage station, and automatically removes a selected cassette from the storage station and deposits it on the print carriage. The apparatus includes cassette holders at the storage location and a cassette holder mounted to the print carriage.

Abstract: A belt drive tensioning system for a motor drive positioning system, especially for X-Y digital plotters. The tensioning system employs spring-loading involving pivoting motion of a motor-mounted plate relative to a fixed plate to accurately preset and maintain constant the desired belt tension. A preferred embodiment provides a self-contained modular unit using two pivot bushings interconnecting the two plates.

Abstract: Apparatus, for use in conjunction with a digital plotter incorporating controlled multiple markers to create displays, for determining the position of the markers along axes of movement, comprises a detector assembly disposed at a fixed axial position relative to the plotter, and a driver for moving a marker relative to the detector assembly. The detector assembly includes means for detecting movement of the marker relative thereto and producing signals indicative of the movement. A processor interprets the signals for determining an axial position of the marker and optionally detects and compensates for a variation in the axial position of a current marker relative to the axial position of a prior marker.