| 摘要 |
<p>A security device (1O, 21, 31, 41) for a premises is provided for the time when the usual occupants of those premises are not in attendance. The security device (1O, 21, 31, 41) has an operating unit (11, 22, 32, 42) and at least one device (12, 23, 33, 34, 43, 50, 54), such as lamp, radio or the like, switchable between on and off conditions. The operating unit (11, 22, 32, 42) has a signal generator (13, 25, 36, 46) and the switchable device (12, 23, 33, 34, 43, 50, 54) has a signal receiver (16, 29), whereby on receipt of a signal (S) from the signal generator (13, 25, 36, 46) the signal receiver (16, 29) is operable to switch the switchable device (12, 23, 33, 34, 43, 50, 54) between on and off conditions. An activating device (18, 30, 37, 47) is operable to cause the signal generator (13, 25, 36, 46) to generate a signal (S) when the activating device (18, 30, 37, 47) senses a predetermined circumstance, such as the ambient light (L) falling below a predetermined level, or at a preset time.</p> |
