Abstract: The tension in a filament is measured by deflecting the filament between two outer contact elements by a centrally-located deflecting contact element. A computer receives signals related to the displacement of the contact members, the force on the deflecting contact member and a plurality of relative displacement intervals of the contact elements. The computer determines a plurality of incremental force values related to the force on the deflecting contact element at each of the displacement intervals and calculates the tension in the filament based on the selected incremental force values.

Abstract: A large-format plotting device is provided for transferring an image to a relatively large sized medium. A data processing device is used to divide the surface of the medium into a plurality of relatively narrow segments. A beam sweeping device, which can include a high energy beam such as a laser beam, is provided for sweeping the beam the width of the segment. The data processing device causes the beam to turn on and off to define a portion of the desired image. A movement mechanism is included to either move the beam generating device or the support for the medium at a desired velocity so that each sweep of the beam will produce a raster line whereby the entire segment will be swept forming a plurality of parallel raster lines covering the entire segment. The movement mechanism also includes placement mechanism for laterally moving the medium support or beam generating device to the next adjacent segment in sequence until the surface of the entire medium has been imaged.

Abstract: An apparatus codes a scanned document locally representing each graphic element within a prescribed measure of accuracy by a trapezoidal approximation. The invention also includes a method for similarly coding a scanned document. The apparatus determines whether each scanned run is indicative of a Y- or .lambda.-junction, the termination of an old, or the commencement of a new graphic element, and whether a new linear approximation is necessary. The invention in a preferred embodiment recognizes symbols by determining the center of mass and maximum extremity of a symbol candidate, and comparing it to a reference library after normalizing with respect to scale, orientation and center of mass. In a preferred embodiment, an adaptive threshold parameter governs coding so as to reject noise and optimize a pair of linear predicters in a small number of scans. In a further preferred embodiment the accuracy of the linear predicters is refined so that the error is exponentially bounded.