Balance corrector for scanner motors and balance correcting method thereof

A balance correcting method for an inner rotor type scanner motor for rotation-driving a rotary polygon mirror for performing deflection scanning, wherein said scanner motor is arranged as separable into two units including a rotary unit part for holding a bearing of a rotary member to which said rotary polygon mirror and a drive magnet are fixed on a motor housing and a stationary unit part in which a stator coil and a magnetic member are disposed on a base, said method comprising the steps of:

• separating said scanner motor into the rotary unit part and the stationary unit part;
• mounting the rotary unit part thus separated on a balance corrector;
• rotation-driving said rotary unit part on the balance corrector, which includes a stator portion having a substantially identical structure to the stationary part of said scanner motor;
• and
• measuring an amount of unbalance of the rotary unit part while rotating the rotary unit part on the balance corrector.

A balance corrector for an inner rotor type scanner motor, which is arranged as separable into two units consisting of a rotary unit part for holding a bearing of a rotary member to which a rotary polygon mirror and a drive magnet are fixed, on a motor housing, and a stationary unit part in which a stator coil and a magnetic member are disposed on a base, said balance corrector comprising:

• a mounting portion which is arranged in such a manner that, after separation of the scanner motor into the rotary unit part and the stationary unit part, the motor housing of the rotary unit part may be received in the mounting portion;
• and
• a stator portion having a substantially identical structure to the stationary unit part and disposed in such a location that, when the motor housing of the rotary unit part is received in said mounting portion, said stator portion is disposed opposed to the drive magnet of the rotary unit part on the side of the outer periphery thereof,
• wherein a clearance is provided between said stator portion and said mounting portion in which a device for correcting the balance is to be located;
• and
• said device is manipulated through said clearance to effect balance correction of the rotary unit part in accordance with an amount of unbalance of the rotary unit part rotation-driven by said stator portion.