| 摘要 |
<p>A sign box (1030) has a viewing window (1031) displaying a first sign under reflected light when the interior of the box is not illuminated. The first sign is made up of two sets of opaque dots on a transparent sheet (1020), a first set of a background colour and a second set (1021) of one or more foreground colours. A sheet (1018) is positioned behind sheet (1020), and comprises a sign visible under transmitted light from a fluorescent light source (1010) which has means (1013) to flash the fluorescent lamps (1011 and 1012) on and off.</p> |
