Wire fire control mechanism for a wire matrix printer

Abstract

A wire fire control mechanism is provided for use in a wire matrix printer for controlling the firing of the print wires as the printhead moves across a print receiving medium. This wire fire control mechanism enables printing to be accomplished for a wide range of different printhead speeds. It also enables printing to be accomplished while the printhead is accelerating or decelerating. It further enables dots to be printed at positions which are not dependent on or limited to the fixed points defined by the emitter signals which are used to keep track of the position of the printhead as it moves across the print receiving medium. In a representative embodiment, the wire fire control mechanism includes emitter means for sensing movement of the printhead and producing emitter signals which define fixed points across the print receiving medium. The control mechanism also includes means for providing a target signal for determining a position at which a dot may be printed on the print receiving medium, such dot position not being dependent upon or limited to the fixed points defined by the emitter signals. The control mechanism further includes means for sensing the speed of the printhead and producing a flight time distance signal representing the distance the printhead will move while a print wire is in flight from the printhead to the print receiving medium. The control mechanism further includes means responsive to the target signal, the emitter signals and the flight time distance signal for producing a wire fire signal when the distance between the print wire position and the target becomes substantially equal to the flight time distance.