| 摘要 |
<p>A portable warning sign, warning light, and audible warning system, based on a foldable A-frame stand, has a warning message carried on one or both opposite faces of the stand and warning lights at the top thereof for attracting attention to the message. The warning lights, as LEDs, are battery- or solar-powered and are preferably rechargeable. A motion sensor and speaker for giving an audible warning of the danger to actual passers-by may also be included.</p> |
