Motor drive control device, motor unit, and motor drive control method

A motor drive control device comprising:

• a control unit configured to generate a control signal for controlling driving of a two-phase stepping motor;
• and
• a drive unit configured to drive coils of two phases of the two-phase stepping motor based on the control signal,
• wherein the control unit has, as control modes, a first commutation control mode for commutating the coils according to a target energization time based on a preset commutation condition, and a second commutation control mode for commutating the coils based on a detection result of a zero crossing point of a back electromotive voltage of the coils, and
• the control unit generates the control signal in the first commutation control mode at start of activation of the two-phase stepping motor, and generates the control signal in the second commutation control mode when the detection result of the zero crossing point satisfies a predetermined condition, wherein
• a speed of the two phase stepping motor and an energization angle indicating a magnitude of an electrical angle for energizing one of the coils of the two phases continuously in one direction are set as the commutation condition, and
• in the first commutation control mode, the control unit determines the target energization time based on the speed and the energization angle.