PRINTING APPARATUS

摘要

A printing apparatus for an electronic calculator or the like comprises a first type wheel formed with mathematical operator symbols which is fixed to a spline shaft and a second type wheel formed with digits which is slidably mounted on the spline shaft for integral rotation. A stepping motor rotates the spline shaft for character selection. A carriage is connected to the second type wheel and is movable by a cable wound around drive and take-up spools to move the second type wheel along the spline shaft for serial feed. A single electrical solenoid actuates a printing hammer for printing and subsequently actuates a ratchet and pawl mechanism to serially feed the second type wheel by one character position in one reciprocation of the solenoid plunger. A linkage initially connects the plunger to a first printing hammer associated with the first type wheel to print the mathematical operator and subsequently to a second printing hammer associated with the second type wheel to serially print digits from least significant to most significant.