PLATEN VARIABLE

摘要

PLATEN VARIABLE A platen variable arrangement for use in a typewriter or the like machine is disclosed and includes a coarse platen adjusting member in the form of a knob and a fine platen adjusting member in the form of a wheel. Each adjusting member is readily accessible to the operator and operates to provide distinct rates of platen rotation. Members for coarse adjustment of the platen include the coarse platen adjusting knob coupled to an axial extension of the platen and a sprocket cooperating with a conventional detent to provide platen rotation in controlled step increments. A finer adjustment of the platen is achieved through rotation of the fine adjusting wheel. Members for accomplishing fine platen adjustment include a flexspline having internal spline teeth at one end. The flexspline is rigidly fixed on the axial platen extension to locate the internal teeth in close circumferential relationship with circular spline teeth on a stationary hub member. The teeth on the hub member are fewer in number than the internal spline teeth on the flexspline. The circular pitch used for construction of the respective sets of spline teeth is compatible. A wave generator on an inner surface of the fine platen adjusting wheel frictionally engages an outside portion of the flexspline carrying the internal teeth thereby deflecting the flexspline to engage internal spline teeth with circular spline teeth at spaced localities. Rotation of the fine platen adjusting wheel advances the areas of spline engagement which in turn drives the flexspline about its axis. The drive of the flexspline is transferred to the platen in view of the rigid attachment through a set screw and at a rate substantially reduced to the step increment rate of rotation applied by the coarse adjusting knob.