Bobbin winder device of a sewing machine and method for controlling or regulating the speed of the motor of a bobbin winder device

A bobbin winder device of a sewing machine, the bobbin winder device comprising:

• a motor;
• a spindle mounted on a support and configured to rotate about a spindle axis and which is driveable by said motor, for releasable attachment of a thread bobbin to be filled with sewing thread;
• a motor controller connected to the motor via electrical conductors and configured to control or regulate a rotational speed of the motor;
• a brake pad with a friction surface held on the support so as to be movable, wherein a distance between the friction surface and the spindle axis is variable, such that the friction surface is positionable next to the spindle in a reference position with a predeterminable reference distance from the spindle axis corresponding to a maximum winding radius of the sewing thread to be wound and is displaceable radially outwards from the reference position counter to a force of a restoring element with respect to the spindle axis;
• and
• the motor controller comprises a sensor configured to detect at least one measured variable, which is dependent on a load of the motor, in a driving circuit of the motor and at least one of a) a stored comparison value for said measured variable or b) a stored comparison value for a rate of change of the measured variable over time.