Patent ID: 7893647

Claim:
A system for driving a load element, comprising: a drive motor on a drive shaft of the load element that establishes a drive rotation speed of the load element; a rotation torque sensor on the drive shaft that emits a load torque signal proportional to a rotation torque; a rotation torque influencing device that generates a supplementary torque when the load torque signal deviates from a desired load angle value present when a change has not occurred to a load created by the load element and acting on the drive motor, said supplementary torque being added to a drive torque generated by the drive motor such that a load angle of the drive motor remains substantially constant and uninfluenced by a change of the load; the drive motor comprising a step motor whose motor shaft drives the drive shaft of the load element; the rotation torque influencing device influencing a driving magnetic field for the motor shaft of the step motor such that a phase angle between a position of the motor shaft of the step motor and a magnetic field remains uninfluenced by the change of the load; an activation frequency for motor currents of the step motor being controlled dependent on the load created by the load element; and the rotation torque influencing device generating clock signals dependent on the load change, said clock signals being supplied to the motor controller of the step motor, said step motor generating from the clock signals activation pulses for motor currents of the step motor.