| 摘要 |
<p>A top lid assembly is comprised of a first top lid and a second top lid which can be overlapped with the first top lid, wherein each of the first top lid and the second top lid includes a cover plate and a frame connected with the cover plate, the frame includes at least a first edge girder. When the top lid assembly is closed, the first edge girder of the second top lid is housed within the space defined by the first edge girder of the first top lid substantially. The top lid assembly having above structure can prevent effectively the foreign contaminant from entering the interior volume of the box body through the gap between two top lids or the overlapped area of the top lids with remainder of the box body. Also, at least one drain hole can be provided in the top lid, to facilitate the drainage of the contaminant and to avoid accumulating the contaminant on the top lid.</p> |
