| 摘要 |
An anti-jamming device for windows and doors comprises a capacitive sensing plate connected to one pole, which supplies a variable potential, of an alternating current source (S), the other pole of which is connected to a fixed potential, e.g. earth (3). The sensing plate acts as an electrode (1) and is insulated from electrically conductive parts connected to the fixed potential, which form a second electrode. An intermediate electrode (2) is connected to the electrode (1) formed by the sensing plate and insulated from the parts connected to the fixed potential which form the second electrode. An evaluation circuit (6) responds to the changes in capacitance. To render the anti-jamming device impervious to moisture and dirt, the two electrodes (1, 2) connected to the variable potential can be moved relative to each other and the evaluation circuit (6, 6') responds only to the changes in capacitance of the electrode (3) connected to the fixed potential with respect to the other two electrodes (1, 2), to which an equiphase alternating voltage signal is fed. |
