Method of operating an impact printer having hammer flight time and velocity sensing means.

摘要

In an impact printer including a print wheel (20) having a plurality of selectable character type bearing elements (19) for respectively printing a plurality of characters, said print wheel being rotatable for selectively positioning selected type elements in successive print positions, impact means (18) impellable against the selected elements to drive said elements against the printing medium and means (17) for impelling the impact means against said selected type element, the present invention provides the improvement comprising means (27) for sensing the flight time of the impelled impact means until impact by sensing variations in velocity of said impact means and means responsive to said sensed flight time for controlling the impelling means to vary the flight time. In accordance with another aspect of the present apparatus, means are provided for detecting the coincident engagement of the impact means with a type element by also sensing the velocity of the impact means after the impact means has reached a predetermined coincident engagement position.