| 摘要 |
The invention specifies an apparatus and a method for monitoring a building opening which is closed with a closure element (6, 6a . . . 6n) which is not fully transparent. The apparatus comprises a pattern (M), which is arranged on one side of the closure element (6, 6a . . . 6n) or is projected onto this side, and a detection unit (7a . . . 7e) which is aligned with this pattern (M). A comparison unit compares the actual pattern (M) detected by the detection unit (7a . . . 7e) with a desired pattern and triggers an alarm if the difference between the actual pattern (M) and the desired pattern exceeds a predefinable threshold. |
