Multiplexed hammer dot band matrix printer

摘要

Hammers impact dot front elements on a moving band and drive them into a printing medium. The pitch between two dot font elements is assigned to two adjacent hammers in this invention. An electronic control is used so that adjacent hammers cannot be fired simultaneously. Hammers in a bank are divided into two groups with members of each group alternating on a one for one basis along the hammer bank. Hammers which are fired in a group will all be operating on the same relative dot position in their space in the line of print being formed. With prior dot band hammers, additional spacing is allowed between dots on the band to avoid the problem of nipping and crashing of the anvil elements on the back of the dot band into extended faces of adjacent print hammers. This has created a small gap in which no dots can be created. The present invention also provides a means for automatically selecting large or small dots for printing if the print band has large and small size dot font elements alternated serially on it. It is only necessary to choose firing the hammers of the first group or the second group first in order to select large dots or small dots for printing.