Anti-pinch circuit device for an apparatus for automatic movement of sliding windows in a motor vehicle, and corresponding method

An anti-pinch circuit device for an apparatus for automatic movement of sliding windows in a motor vehicle comprising a d.c. electric motor that moves a window (F) so that it slides along guides, said device comprising an electronic control module for controlling said d.c. electric motor, in particular a microprocessor, said electronic control module acting to measure a current (I) of said motor and a position (X) of said window (F), said control module drives reversal of operation of the electric motor if it is verified that said current (I) is higher than a threshold current (Ith) and said position (X) of said window (F) falls within a given zone (APZ) of a path (P) of movement of the window,

• wherein said anti-pinch circuit device measures a back electromotive force (E;
• Em) of the motor, obtaining (140) a value of said back electromotive force (E;
• Em), and the electronic control module calculates the position of the window (F) as a function of said measured value of said back electromotive force (E;
• Em) of the motor,
• wherein said electronic control module is configured to:
• read a starting position of the window (F);
• start a timer;
• read a value of back electromotive force (E;
• EMFUP, EMFDOWN);
• calculate a mean value (Em) of the back electromotive force;
• verify the value of said current (I) of the motor and,
• if said current (I) is lower than a threshold current (Ith), returning to the step of reading the value of back electromotive force (E;
• EMFUP, EMFDOWN);
• if the current (I) of the motor is higher than a threshold current (Ith), stopping the timer, obtaining a time (tw) of sliding of the window (F);
• calculate a speed of the window (v) as ratio between the back electromotive force (Em) measured and a coefficient of proportionality (Ke) associated to the automatic-movement apparatus;
• and
• calculate the position of the window (F) as product of said speed of the window (v) and of the time (tw) of sliding of the window (F).