Control device for stepping motor and control method for stepping motor

A control device for a stepping motor configured to rotate a rotor by controlling an excitation current in each of one phase and another phase of two-phase coils, the control device comprising:

• hold control unit configured to move a rotor of the stepping motor to a predetermined initial position during a hold period at a startup of the stepping motor;
• and
• normal control unit configured to perform one-phase excitation operation of the stepping motor after the end of the hold period, wherein
• from when the hold period is started until the hold period ends, the hold control unit gradually increases an absolute value of the excitation current in the one phase such that the amount of change in the excitation current per unit time is smaller than or equal to a first predetermined value,
• from when the hold period is started until a predetermined time elapses, the hold control unit gradually increases an absolute value of the excitation current in the other phase such that the amount of change in the excitation current per unit time is smaller than or equal to the first predetermined value, and
• by the time the hold period ends after the predetermined time has elapsed, the hold control unit causes the excitation current in the other phase to reach zero, and wherein
• when the hold period ends, the normal control unit starts to perform one-phase excitation operation of the stepping motor such that the excitation current flows in the one phase first with the same polarity as at the end of the hold period.