PURPOSE: To ensure a stable print pressure by controlling the energization time width of a drive current of a hammer drive solenoid based on the movement of a print hammer.
CONSTITUTION: A print hammer 6 is provided on a hammer drive solenoid 5 while charged with a force in one direction through a return spring 7 and is moved in the opposite direction to strike a type when the solenoid 5 is energized. A code plate 8 is provided at the rear end of the print hammer 6 and a photoelectric sensor 9 is disposed sandwitching the code plate 8. When the hammer drive solenoid 5 is energized to move the print hammer 6 by a given value, the photoelectric sensor 9 outputs a detection signal C to reset FF3. As the output Q of the FF3 goes to a lower level, the drive current fed to the hammer drive solenoid 5 from a constant current driving circut 4 is cut off and the signal wavelength of the output Q of the FF3 becomes as shown by (b). The FF3 and the constant current driving circuit 4 make up a solenoid drive generation circuit.
ISE SEIJI
UCHIDA SHIGERU
SUGIMOTO KIYOUJI
TAKANO AKIO
NIPPON TYPEWRITER