| 摘要 |
Laminated windscreens with an electrically conductive coating between layers of the windscreen are commonly provided with one or more small apertures or transmission windows in the coating to allow the passage of electromagnetic radiation. The present invention reduces the formation of localised hot spots in such heated windscreens by dividing the conductive coating 2 into at least two zones 7, 8, 9 separated by divisions 10, 11 in the coating, and arranging the busbars so as to ensure a smooth current distribution within each zone. The transmission window 6 may be located in a central zone 8 of the windscreen and the adjacent busbar 4 placed around three sides of the window. In a preferred embodiment the voltage applied in this central zone is set by means, for example, of resistors 12 and 13 (fig.3) so as to maintain approximately equal temperatures in all the zones. |
