Patent ID: 8072166

Claim:
A brushless DC motor, comprising: a first drive member including M phase coil groups, each phase having N electromagnetic coils where M is equal to three and N is an integer of 2 or greater; a second drive member including a plurality of permanent magnets, the second drive member being movable relative to the first drive member; a magnetic sensor disposed on the first drive member, the magnetic sensor detecting a relative position of the magnets and the coils; and a drive control circuit generating an application voltage to drive the coils based on an output signal of the magnetic sensor, wherein the first drive member has 2(MÃ—N) spaced apart magnetic yokes, each magnetic yoke including: a magnetic body core, and a plate shaped member that is laterally unbalanced relative to a center of the magnetic body core, wherein all of the plate shaped members are laterall unbalanced in a common direction relative to the centers of the magnetic body cores, each phase electromagnetic coil is coiled on a magnetic yoke regularly selected at a ratio of 1 to 2 from among all the magnetic yokes, the magnetic sensor is disposed between the magnetic yokes and spaced apart from inner edges of the magnetic yokes, and the plate shaped member of the magnetic yoke of the first drive member provides stop position regulation by pulling the magnetic yoke to one of the permanent magnets when the brush less DC motor stops, so that a center of each permanent magnet stops at a position displaced from the center of each magnetic body core.