Drive apparatus

Drive apparatus comprising a stepper motor, power supply means for supplying drive pulses to said motor for effecting sustained drive of said motor, and start control means operable to perform a start sequence in which it causes the power supply means to supply said drive pulses initially at a low frequency and said frequency is increased at a relatively low rate for an initial period determined by the speed of rotation of the motor and subsequently at a relatively high rate.

Drive apparatus comprising a stepper motor, power supply means for supplying pulses to said motor for effecting sustained drive of said motor, start control means operable to control said power supply means to perform a start sequence for said motor, detector means to detect whether said motor has started, and timing means for providing a time out signal at the end of a time-out interval from the beginning of the start sequence, said control means being responsive to said detector means and said timing means to restart the start sequence and reset said timing means in the event the said timing means provides said time-out signal before said start control means receives a signal from the detector means indicating the the motor has started.

Drive apparatus comprising a motor, means for supplying a first signal at a reference frequency representing a speed at which said motor is to be driven, means for supplying a second signal having a frequency representing the actual speed of the motor, first and second counters arranged for receiving respectively said first and said second signals, means for obtaining a further signal representing the difference in the number of cycles of said first and second signals counted by said first and second counters respectively, and means for controlling the speed of the motor in dependence upon the value of said further signal.

Drive apparatus comprising a motor, means for supplying a first signal at a reference frequency representing a desired frequency of revolution of said motor, means for providing a second signal having a frequency representing the actual frequency of revolution of said motor, said frequencies of both of said first and second signals being at least 100 times said frequency of revolution, first detector means for detecting the difference between said frequencies of said first and second signals, second detector means for detecting a phase difference between said first and second signals, third detector means for detecting whether the frequency difference is within predetermined limits, and control means responsive to the third detector means to control the speed of the motor in accordance with said frequency difference when said frequency difference is outside predetermined limits and in accordance with said phase difference when said frequency difference is within said predetermined limits.