Drive control device for a stepper motor and drive control method of the stepper motor

A stepper motor control device, comprising:

• a sensor that detects physical quantities;
• and
• a control device that controls an operation of a stepper motor based on data corresponding to the physical quantities sent from the sensor,
• wherein the control device implements
• a target rotational angle computation process that calculates a target rotational angle of a drive shaft of the stepper motor based on data corresponding to the physical quantities sent from the sensor,
• a target rotational angle change computation process that calculates a target rotational angle change which is a difference between a present rotational angle of the drive shaft of the stepper motor and the target rotational angle, and
• a divisional target rotational angle computation process that equally divides the target rotational angle change by a first divisional target rotational angle within a range not exceeding a rotational limit for loss of synchronism of the stepper motor;
• wherein the control device is a drive control device of the stepper motor that drives the stepper motor by supplying to the stepper motor a second divisional target rotational angle which is a value calculated by the divisional target rotational angle computation process as a rotational angle per one control period;
• wherein the divisional target rotational angle computation process divides the target rotational angle change by the first divisional target rotational angle within the range not exceeding the rotational limit for loss of synchronism of the stepper motor to calculate a “quotient” and a “remainder” thereof;
• and
• wherein the drive control device of the stepper motor sets the “quotient” to “quotient +1” in the case the “remainder” is not 0 and obtains a second divisional target rotational angle differing from the first divisional target rotational angle to drive the stepper motor based on the second divisional target rotational angle.