Motor control device

A motor control device for controlling a plurality of stepping motors, said motor control device comprising:

• a pulse generator which outputs clock pulses of a predetermined frequency;
• a clock controller which outputs various excitation phase waveforms in accordance with clock pulses of said pulse generator inputted thereto;
• a selector which selects one of said stepping motors;
• a driver which drives a thus selected stepping motor by supplying electrical current to the selected stepping motor according to the excitation phase waveform outputted by said clock controller;
• a controller counter which stores a count value indicating the excitation phase waveform of the clock controller;
• a plurality of motor counters respectively corresponding to said plurality of stepping motors, each of said motor counters storing a count value indicating the excitation phase waveform of its corresponding stepping motor;
• a comparator which compares the count value of the controller counter with the count value of the motor counter of a first stepping motor of said plurality of stepping motors in case the first stepping motor is to be selected by said selector;
• and
• a controller which, when results of comparison by said comparator shows different excitation phase waveforms, controls said selector so that the selector selects none of the stepping motors until the excitation phase waveform of the clock controller matches the excitation phase waveform of the first stepping motor, and thereafter selects the first stepping motor to drive the first stepping motor.

A motor control method for controlling a plurality of stepping motors, said motor control method comprising:

• a first step of outputting clock pulses of a predetermined frequency;
• a second step of outputting various excitation phase waveforms in accordance with the clock pulses thus outputted in the first step;
• a third step of selecting one of said stepping motors;
• a fourth step of driving the thus selected stepping motor by supplying electrical current to the selected stepping motor according to the excitation phase waveform outputted in the second step;
• a fifth step of storing a count value indicating the excitation phase waveform thus outputted in the second step;
• a sixth step of separately storing for each of said plurality of stepping motors a count value indicating the excitation phase waveform of a corresponding one of the stepping motors;
• a seventh step of comparing the count value stored in the fifth step with the count value of a first stepping motor of said plurality of stepping motors stored in the fifth step;
• and
• an eighth step of selecting none of said stepping motors when the results of comparison in the seventh step shows different excitation phase waveforms, and thereafter, when the excitation phase waveform indicated by the count value in the fifth step matches the excitation phase waveform of one of said stepping motors, selecting said one of said stepping motors to drive said one of said stepping motors.