| 摘要 |
PURPOSE:To suppress a noise and a heat as low as possible in a stepper motor by controlling a high speed printing when the number of characters to be printed is less, and controlling a low speed printing when the number of characters is many. CONSTITUTION:The winding of a stepper motor 8 is connected through transistors 251-254 for changing the phases and current controlling transistors 28, 29 with a power source. A current is detected by current detecting resistors 26, 27 to control the transistors 28, 29. Here, when it is set to a printing mode that the number of characters to be printed per unit length is many, current amounts flowing to phase coils are controlled to be reduced to drive stepping at low speed. When it is set to a printing mode that the number of characters to be printed per unit length is less, current amounts flowing to phase coils are controlled to be increased to drive the motor at high speed. |
