| 摘要 |
PURPOSE:To obtain the holding torque provided with a stabilized characteristic by setting the duty ratio of pulse signals in proportion to the number of excitation coils. CONSTITUTION:A discrimination circuit 18 in response to driving signals A, A' and B, B' discriminates the driving state from time to time to be required, and a discrimination signal D indication the result of discrimination is applied to a pulse generator 17 as a duty ratio controlling signal. One or the other of two duty ratio conditions, such as the first duty ratio condition having a relatively bigger duty ratio in proportion to single-phase drive and the second duty ratio having a relatively smaller duty ratio in proportion to two-phase drive, is responsed to the discrimination signal D to be set. Therefore, the holding torque is kept in constant regardless of the driving conditions, and the overheating of excitation coils and the consumption of consumer power are effectively prevented. |
