Hitachi Koki Co., Ltd.

Mitsuru Kawakami

Toshiyuki Suzuki

Masami Iwama

Kohichi Yageta

To prevent effective print speed from being lowered, a counter is provided for each of a plurality of print hammers. A number of times a print hammer is driven during one print phase having a predetermined period of time is counted by the counter. The counted value is compared with a reference value, and when the counted value has reached the reference value during the print phase, driving of the print hammer is halted until the end of the print phase. A reference value is changed based on the number of times the print hammer is driven during a previous print phase immediately before the present print phase. The reference value represents an allowable number the print hammer can be driven during each of successive print phases.

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Hitachinaka, Japan

Mitsuru Kawakami