| 摘要 |
PURPOSE:To prevent step-out of a stepping motor from occurring and reduce the size of the motor and the cost, by providing a torque limiter and a one-way clutch in a power-transmitting mechanism for transmitting the motive power of a stepping motor to a ribbon base. CONSTITUTION:When the stepping motor 5 is driven in the direction for bringing the ribbon base 3 into contact with an adjusting screw 15 by designating a number of steps to be not less than 30 while allowing for margins, the motor 5 is rotated based on the inputted pulses even after the base 3 makes contact with the screw 15, while the base 3 remains stationary under the slipping action of the torque limiter 30, and the motor 5 is rotated by a predetermined number of steps without any step-out, and is stopped. When the motor 5 is rotated in the opposite direction, the base 3 is moved upward, and a desired one of color zones 20, 21, 23 of a ribbon 19 is opposed to a printing position. During the upward movement, when the load is large and frictional resistance in the power-transmitting mechanism 17 is large, the torque limiter 30 slips, but the one-way clutch 27 securely transmits the motive power from a gear 7 to a gear 8. |
