Controller of stepping motor, control method of stepping motor, and stepping motor drive controlling system

A control method of a stepping motor, the method comprising:

• generating a data table of a threshold by using values of induced voltage at frequencies of switching signal that changes a set value of a drive current, the threshold being proportional to a frequency of the switching signal within an operation region in which the frequency of the switching signal is lower than a predetermined frequency, the values of the induced voltage including a first induced voltage generated at a first frequency of the switching signal and a second induced voltage generated at a second frequency of the switching signal;
• and
• comparing the threshold and an induced voltage that is detected at a frequency lower than the predetermined frequency with each other within the operation region in which the frequency of the switching signal is lower than the predetermined frequency;
• and
• controlling a value of the drive current in accordance with a result of the comparing.

A stepping motor drive controlling system comprising:

• a stepping motor including an exciting coil that generates a magnetic field by a drive current;
• and
• a controller that controls the drive current, wherein
• the controller includes:
• a table generating unit that generates a data table of a threshold by using values of induced voltage at frequencies of switching signal that changes a set value of a drive current, the threshold being proportional to a frequency of the switching signal within an operation region in which the frequency of the switching signal is lower than a predetermined frequency, the values of the induced voltage including a first induced voltage generated at a first frequency of the switching signal and a second induced voltage generated at a second frequency of the switching signal;
• and
• a current controlling unit that is configured to:
• compare the threshold and an induced voltage that is detected at a frequency lower than the predetermined frequency with each other;
• and
• control a value of the drive current in accordance with a comparison result.