Hammer locating and operational means

A chain impact printer comprising:

• an array of hammers, each hammer being positionable at a plurality of hammer operating positions along a line of printing, said array of hammers being movable;
• a stepping motor operable to position said array of hammers along said line of printing, said stepping motor having a plurality of step positions between each adjacent pairs of hammer operating positions along said line of printing;
• a position transducer cooperating with said stepping motor to indicate when said array is a first predetermined number of steps away from one of said plurality of operating positions;
• and,
• a controller executing a movement sequence to move said array from a first operating position to the next adjacent operating position, said movement sequence including commanding said stepping motor to perform said first predetermined number of steps, said controller receiving the output of said position transducer at the end of said first predetermined number of steps to indicate a first state if said hammer array is in the correct stepping position to subsequently arrive correctly at the next operating position, and a second state if the hammer array is not in its correct stepping position to arrive correctly at the next operating position, said controller responding to said position transducer output being a first state by commanding said stepping motor to move a second predetermined number of steps to bring said array to said next adjacent operating position, and responding to said second state to command said motor to perform a position correction sequence by commanding said stepping motor to perform individual steps and monitoring said output of said transducer for each of said individual steps until a step is found at which said transducer provides a first state indication that said hammer array is in the correct stepping position.