| 摘要 |
<p>PURPOSE:To correct the deviation of position information by not only stopping a driving means but also decreasing the counted value of a counting means when the present period is shorter than the preceding period. CONSTITUTION:When a brake operation is started at a time t3, a rotation direction inverting signal is applied to a motor to put on the brake for reverse, and it is checked in this state whether an FG pulse is inputted or not; and if the FG pulse is inputted, the length of a period TFG of the FG pulse is detected, and the length of the present TFG (TFG2) and that of the preceding TFG (TFG1) are compared with each other; and when TFG2<T2, a pulse PD is generated on a basis of the FG pulse and the brake is released when TFG2>TFG1. A prescribed threshold time TFG2<TFG1 is detected at, T2 the reverse of the motor is decided to set a flag indicating abnormality and the brake is released immediately to prevent reverse runaway of the motor.</p> |
