Method and device for limiting a number of times each print hammer is driven during a predetermined period of time

A printer comprising:

• a plurality of print hammers that are selectively driven in accordance with print data, thereby making an impression of dot on a print medium;
• a counter, provided for each of said plurality of print hammers, that counts a number of times a print hammer is driven;
• a timer that repeatedly measures a predetermined period of time;
• reference value changing means for changing a reference value based on the number of times the print hammer is driven during a previous print phase defined by the predetermined period of time measured by said timer immediately before measuring a present print phase that is also defined by the predetermined period of time measured by said timer wherein the reference value represents an allowable number the print hammer can be driven during each of successive print phases;
• and
• print halting means for halting driving of the print hammer when a number of times the print hammer is driven during the present print phase has reached the reference value changed by said reference value changing means, driving of the print hammer being halted until expiration of the present print phase.