| 摘要 |
PURPOSE:To obtain a speed control signal of high accuracy by using parallel rays emitted from a luminous body. CONSTITUTION:When a rotor 22 is rotated by supplying a driving power source to a stator winding 20, a rotation axis 3 and a rotary disk 4 are rotated, and parallel rays from a luminous body 9 are received by a light receiving body 6 through a rotary slit 4a of the disk 4 and a fixed slit of a fixed slit plate 5. In this case, since light emitted from the luminous body 9 is parallel rays, the light quantity for passing through the fixed slit through the slit 4a is proportional to a transmission area of the slit 4a and the fixed slit, and in case when a light and darkness pitch of the slit 4a and slit width of the fixed slit are the same, a triangular wave signal obtained from the light receiving body 6 becomes an extremely sharp triangular wave shape. This triangular wave signal is outputted as a speed control signal consisting of a voltage level value by a speed control signal generating circuit, and a motor 31 can be held at a constant speed. |
