Brush, commutator, and commutator device

A commutator having a plurality of commutator segments, which makes contact with a brush, each of the commutator segments comprising:

• a low-resistive layer made of a low-resistive material;
• and
• a high-resistive layer made of a high-resistive material having a specific resistance higher than that of the low-resistive material, wherein
• the high-resistive material contains an inorganic substance, which has a specific resistance higher than that of the low-resistive material, more than 20 wt % with respect to a total weight of the high-resistive material.

A commutator deice comprising:

• a commutator having a plurality of commutator segments, and disposed to rotate in a direction when operated;
• and
• a pair of brushes disposed to make contact with the commutator segments, wherein
• one of the plurality of commutator segments and the pair of brushes is made of a material containing graphite and carbon fiber, and the other one of the plurality of commutator segments and the pair of brushes is composed of a low-resistive layer and a high-resistive layer, wherein
• the low-resistive layer is made of a low-resistive material and the high-resistive layer is made of a high-resistive material, and the high-resistive material contains an inorganic substance more than 20 wt % therein and has a specific resistance higher than that of the low-resistive material.