Generally, printers use stepper motors. Laser printers and inkjet printers mainly use DC brushless motors (some may also use brushed motors), while dot matrix printers typically use stepper motors. Small-sized dot matrix printers usually use permanent magnet stepper motors, whereas larger models use hybrid stepper motors.
Stepper motors do not require feedback to control position and speed, and they are relatively low in cost. However, their speed is limited, so high-speed printers typically use servo motors, while stepper motors are suitable for lower-speed applications.
Stepper motors generally have limited overload capacity, whereas AC servo motors offer strong overload capability. For example, in a Panasonic AC servo system, both speed and torque overload capacities are supported. The maximum torque can reach up to three times the rated torque, which helps overcome the inertia of loads during startup.
Since stepper motors do not have this level of overload capacity, larger torque motors are often selected to overcome inertia. However, such high torque is not required during normal operation, which leads to energy inefficiency.
Stepper motor control is open-loop. If the starting frequency is too high or the load is too heavy, it may cause step loss or stalling. If the stopping speed is too high, overshoot may occur. Therefore, acceleration and deceleration must be properly controlled to ensure accuracy.
In contrast, AC servo drive systems use closed-loop control. The driver directly receives feedback signals from the motor encoder and manages both position and speed loops internally. As a result, issues such as step loss or overshoot are generally avoided, making the control performance more reliable.
