| 摘要 |
<p>A door includes a panel 10 having a window aperture in which a window 11 is fitted. The window comprises a material (13, fig 2) which is normally configured in a first state to partially or fully obscure vision through the window. The door further comprising means, such as a control unit 19, for reconfiguring or switching the window into a second state, in which vision through the window is unobstructed. The said material of the window is preferably liquid crystal, such as PDLC. The operation of the window is preferably configured to prevent or deter actuation by persons other than in the event of a fire or other emergency. Preferably the window is reconfigured by an actuator 21, optionally comprising a key switch, keypad or breakable cover.</p> |
