| 摘要 |
PURPOSE:To prevent sunlight from entering through an observation window to normally protect internal apparatuses from deterioration caused by the sunlight and, if required, facilitate observation of the internal apparatuses with a simple operation. CONSTITUTION:A variable light transmission sheet 3 which is composed of a pair of transparent conductive films having conductive surfaces on their inner sides and which has suspension of liquid crystal suspension between the transparent conductive films is attached to an observation window 2 through which internal apparatuses can be observed. The variable light transmission sheet 3 is transparent only while a voltage is applied. For that purpose, a switch 5 for the variable light transmission sheet 3 is provided near the observation window 2 and a solar cell 4 for the variable light transmission sheet 3 is provided on the outside of an outdoor switchboard 1. |
