Print hammer actuating device

Abstract

An impact printer utilizes a single print hammer which is loaded with a selected type chip transferred from a rotatable carousel cartridge containing plural type chips. A single solenoid motor is energized to effect chip transfer, the loading of a spring to effect subsequent return of the chip to the cartridge, and the loading of an energy storage spring utilized to power the print hammer toward a platen. Completion of the chip transfer to the print hammer releases the print hammer to be powered by the storage spring until the solenoid motor is de-energized. The solenoid armature provides a reaction force to the storage spring only during solenoid energization. The duration of solenoid energization thus controls the impact force of the print hammer and is varied in accordance with the character area of the selected type chip and with the desired print density. An interlock latch prevents return motion of the type chip positioning and transfer mechanism during printing and during return motion of the print hammer. A restraining latch restrains the print hammer in its chip receiving position until the chip transfer to the print hammer is completed. The latching member of this latch is resiliently urged to restore the type chip to the cartridge upon return of the print hammer to its chip receiving position. An additional mechanism insures clearance of the latch member from the cartridge upon return of the type chip thereto.