| 摘要 |
The drive arrangement comprises circuitry for detecting the passage of the motor current through a relative maximum while a drive pulse is applied to the motor. The duration of the drive pulse, which ordinarily has a predetermined minimum duration T0, is increased by a predetermined amount DELTA T if no maximum is observed during the time T0. If no current maximum is detected during the detection pulse, the detection pulse is prolonged by one or more increments of predetermined lengths, up to a predetermined maximum duration. The drive pulse is also prolonged each time the detection pulse is prolonged. In one preferred embodiment, a memory circuit (13), which is reset after each drive pulse, which is reset after each drive pulse, stores the maximum value of the motor current observed during a given pulse as of a given instant. A comparator (12) compares the stored value to the instantaneous value of the current, the comparator output changing state when the current falls after passing through a relative maximum. <IMAGE> |
