| 摘要 |
<p>According to the present invention is disclosed a method and a device for a glass pane (12) utilizing locally generated first and second electric or electromagnetic fields and in which changes due to an introduced electrically conducting object by an electronic measurement device. The fields are produced by an electronic unit and by means of a transparent but conducting layer (14) preferably applied to the inner surface of the glass pane to be guarded. The conducting layer (14) on the pane simultaneously constitutes an electrode for sensing of changes in the thus generated fields due to the presence of an electrically conducting body. Additionally the electronic unit performs by means of said electrode, thus covering the entire glass pane, a capacitive measurement whereby further is detected if a conducting object, sensed by the first and second electric or electromagnetic fields will come very close or in contact with the pane. By means of the applied electric or electromagnetic fields and the capacitive measurement different surveillance zones (1, 2, 3) are defined and having different levels of alarm.</p> |
