| 摘要 |
PURPOSE:To detect a speed of a disk type commutator motor in a simple structure by integrally molding a circular unit alternately having transparent parts and opaque parts at a fine pitch when molding an armature with plastic, and detecting the intermittent interruption of the light via a photocoupler. CONSTITUTION:When an armature 6 having a plurality of armature coils 7-1- 7-3 is molded with plastic, a rotating speed detecting scale 13 having slots 15 of a fine pitch on the circumference is integrally molded. Slits 15 are formed by alternately arranging transparent parts and opaque parts, punching by a press or etching. An index 16 having slots 17 at the same pitch as the slits 15 is mounted on part of the portion corresponding to the scale 14 inside a body case 2. Two sets of photocouplers 18, 20 and 19, 21 are provided at 90 deg. of displaced phase between the scale 13 and the index 16. In this manner, the rotating direction and speed of the rotor can be detected in a simple structure. |
