Electric window safety system

摘要

In a window system having a safety mode whereby motion is reversed when an obstacle is encountered 116, the safety mode is disabled when the window is nearly closed thus preventing erroneous actuation eg when the window meets the seal. Reliable operation is ensured by measuring the position of the window directly 113 rather than by determining the position from the motor output. In the safety mode, window motion is reversed when the motor speed falls below a reference level thus indicating the presence of an obstacle. In an alternative embodiment (figure 12) the reference value is variable 42 in dependence upon the detected window position.