Circuit arrangement and method for operating an adjusting device

A method for operating an adjusting device driven by an electric motor, which drives at least one adjustable part at which the danger that an object or body part will become caught originates, said method comprising at least the following steps by using an evaluation arrangement, ascertaining at least one characteristic variable of the adjusting device as a standard for the adjusting force or adjusting torque;

• comparing the at least one variable with at least one limit value and outputting an overload signal if the limit value is exceeded;
• by use of a position detector, furnishing a position signal that represents a position of a part to be adjusted of the adjusting device;
• defining the electrical power made available to the electric motor (10) as a function of a specified spring rate of a caught object or body part, at a value that makes it possible to adhere to a specifiable maximum catching force;
• subdividing the adjustment travel of the part (12) to be adjusted into a predetermined number of travel path;
• intervals (I), whose length is considerably shorter than the total adjustment travel path and further outputting an overload signal if, in a specified number of successive travel path intervals (I), a continuous change in the ascertained standard for the adjusting force or adjusting torque in the direction of exceeding a limit value has occurred.