| 摘要 |
A first presence detector is used, belonging to a first category, such as a sound wave receiving device (51), which on detection of sound waves within a predetermined first frequency range (0-3 Hz) initiates the activation of the light-producing unit (2). The first presence detector firstly indicates and activates the light-producing unit directly before a person enters the restricted room (1). The activation time (t1) of the light-producing unit is limited on activation from the first detector. A second presence detector (52) of a second category indicates the presence of a person within the restricted room and thereby maintains activated the light-producing unit activated by the first presence detector. When the second presence detector indicates the absence of persons, the light-producing unit is deactivated. |
