In FIG. 5, B1 and B2 represent two brushes 21. Positions of the brushes B1 and B2 are shifted by 90 degrees with respect to the rotation axis C. One brush 21 is connected to a positive pole of a power supply, and the other brush 21 is connected to a negative pole of the power supply. Each of the brushes B1 and B2 is connected to one of the commutator pieces C1 to C6. Among the six commutator pieces 9, the commutator piece 9 connected to the brush 21 varies according to the rotation angle. For example, a combination of the commutator pieces 9 connected to the brushes B1 and B2 varies as (C6C1, C2), (C1, C2), (C1C2, C3), (C2, C3) and so on as the rotor 6 rotates. With such a circuit configuration, the rotor 6 is appropriately rotationally driven with high torque.
[B. Functions and Effects]
FIG. 6A is a view illustrating a brush motor (with four poles and six slots) as a comparative example. In this brush motor, the number of coils 7 is 6, which is more than that in the first example, the number of pairs p of magnet magnetic poles 5 is two pairs, which is identical to that in the first example, and a magnet angle θM is slightly smaller than 90 degrees. On the other hand, a blade angle θW is only 60 degrees at the maximum since the number of coils is 6, and the blade angle θW becomes smaller than the magnet angle θM. As a result, a magnet magnetic flux is insufficiently picked up, and it is difficult to effectively utilize the magnetic flux.
