Motor drive circuit

A motor drive circuit comprising:

• an advance angle setting correcting device which has a correction reference cycle predetermined according to a reference advance angle count value, in which a correction amount is calculated as a ratio of the correction reference cycle to a cycle of a detection signal indicating a detected frequency proportional to a rotation speed of a motor, and in which an advance angle setting signal is obtained in such a manner that the correction amount is multiplied by a proportionality factor;
• and
• an advance angle setting device in which the advance angle correction value is added to the reference advance angle count value thereby outputting an advance angle setting signal,
• wherein a drive command signal containing a rotation speed information based on a target rotation speed is fed to the motor drive circuit from outside, the rotation speed of the motor is variably controlled in response to the drive command signal, and wherein the detection signal indicating a detected frequency proportional to the rotation speed of the motor is fed to the motor drive circuit from a rotation speed detecting device attached to the motor.