When a brushed motor (referred to as motor only) is driven, brush noise is generated due to the discharge in accordance with the contact between the brush and the commutator, and the noise affect other electronic devices. Since electrical abrasion that is one of the brush abrasions occurs due to the brush noise, the durability decreases. Therefore, as a countermeasure to address the problem of the brush noise, an LC filter or a ferrite element is inserted inside or outside the motor to reduce the noise. For example, in JP-UM-A-6-15520, a structure is adopted in which a resistance or a series circuit of a resistance and a capacitor are connected to the choke coil of a direct winding commutator motor in parallel.
USPTO Backgrounds
USPTO Backgrounds