| 摘要 |
PURPOSE:To reduce the number of components and to shorten the axial length of a motor by alternately forming a reflecting surface and a nonreflecting surface on the surfaces of multipolar magnet, and disposing a light emitting element and a photoreceptor for detecting a speed oppositely to the surfaces. CONSTITUTION:Reflecting surfaces 13 made of flat surfaces and nonreflecting surfaces 12 made of oblique surfaces are alternately formed circumferentially on the surface of a multipolar magnet 11. A light emitting element 27 and a photoreceptor 28 are mounted oppositely on the surfaces, and the rotating speed of a rotor 21 is detected from the period of an output signal obtained by the photoreceptor 28 by the reflected light from the surface 13. Thus, a rotary member for detecting a speed signal can be used also as a rotor (a multipolar magnet) to reduce the number of components and to shorten the axial size. |
