| 摘要 |
PROBLEM TO BE SOLVED: To prevent malfunction of chopping operation at the time of hold of a motor and rotation irregularity at the time of rotation, by installing a noise filter for preventing malfunction of constant current control function and chopping operation in a driving circuit, and controlling time constant of filter in accordance with a driving current and the number of revolution. SOLUTION: A noise filter 403 consists of resistors 403a, b, a capacitor 403c and a switching element 403d, and is constituted of two identical filters for A/A phase and B/B phase, which prevent malfunction of a comparator inside an IC 401 for driving which is to be caused by noise at the time of chopping. The noise filter 403 changes time constant by switching a resistance value with the element 403d. A driving current setting part 404 consists of resistors 404a, b, c and a switching element 404d, divides a power source voltage with the resistors so as to obtain a voltage corresponding to a driving current, and input the divided voltage in the terminals of IC's 401e, f for driving. The driving current value is changed by switching the resistance value with the element 404d. |
