| 摘要 |
PURPOSE:To provide a rotating speed controller of motor utilizing PLL(Phase Locked Loop) control system, which can particularly detect a fault even when a rotating speed of motor is a little lower and does not result in any deterioration of image quality. CONSTITUTION:A rotating data of motor 5 is detected by an encoder 1 and is then outputted to a comparator 2. The comparator 2 then outputs such data to CPU 3 as a frequency data and a phase data. CPU 3 judges, from both data, whether the low speed condition should be continued for a constant period or not although a speed of motor 5 has exceeded the reference value. When the low speed condition is continued for the constant period, it is judged as a fault is generated in the motor 5 or load 10. Thereby, a fault of motor or load can be detected under the condition that the motor 5 is rotating at a speed which is low but exceeds the reference value. |
