Patent ID: 8536757
Filing Date: 2013-09-17
Classification: G02B,H02K

Abstract:
1. An inner rotor-type three-phase brushless DC motor provided in a lens barrel comprising a rotor provided with a plurality of magnetic poles divided equally in a circumferential direction at an outer peripheral portion of the rotor and a stator separately arranged along an outer peripheral side of the rotor, wherein the stator is provided with M−n (wherein, n is an integer equal to or larger than 1) stator sections each provided with three stator poles each having different phases, the rotor and stator are mounted on a base piece, which has a shape comprising two substantially concentrically arranged circular-arc sides with different radii seen in the direction of the axis of rotation of the rotor, the rotor and stator being mounted in an area between the two circular-arc sides of the base piece, when a phase is supplied to the stator poles in the two stator sections in order of first, second, and third phases in one direction perpendicular to a central stator pole for one of the stator sections seen in a direction of an axis of rotation of the rotor, a phase is supplied to the stator poles in order of second, third, and first phases in the same direction perpendicular to the central stator pole for the other stator section seen in the direction of the axis of rotation of the rotor, and the rotor is provided with 4M magnetic poles and the total number of stator poles of the stator is 3(M−n), wherein, M is an integer equal to or larger than 3, n is an integer equal to or larger than 1 and (M−n) is an integer equal to or larger than 2.