| 摘要 |
<p>Security apparatus for alarming an aperture (212) having a movable closure member (215) therein, said apparatus including a first unit (216) for location to one side of the aperture (212) and the closure member (215), a second unit (218) for location to another side of the aperture (212) and the closure member (215), a radiation emitter (225) in association with the first unit (216), a radiation sensor (230) in association with the first or the second unit (216 or 218), and reflector means (236) to reflect radiation from the emitter (225) towards the sensor (230) and across the aperture (212), characterized in that the closure member (215) has one or more bounding elements that are apertured (213) to permit passage therethrough of the radiation en route from the emitter (225) to the sensor (230) and such that an alarming function can be provided whether or not the aperture (212) is closed by said closure member.</p> |
