Electrically heatable vision unit

摘要

An improved electrically heated vision unit in which heat can be concentrated in a selected zone or zones thereof includes at least one sheet of a relatively rigid transparent material (12) having a ceramic enamel (14) extending along at least two opposite edges on one surface thereof. A bus bar is associated with each ceramic enamel on each edge of the sheet and has at least one narrow portion (18) overlying and bonded to an associated one of the ceramic enamel, and at least one wide portion (20) in part overlying and bonded to an associated one of said ceramic enamel and in part overlying and bonded to said one surface of the transparent material. The narrow portions and the wide portions of the pair of bus bars are in register with like portions on an opposed one of the bus bars. An electrically conductive transparent coating (22) of generally uniform thickness and composition extends between the pair of bus bars with sections thereof between juxtaposed wide portions of the pair of bus bars being bonded only to the wide portions of the bus bars and the one surface of the transparent material, and with other sections thereof between juxtaposed narrow portions of the pair of bus bars being bonded to the narrow portions of the bus bars, the ceramic enamel and the one surface of the transparent material. Structure is provided for supplying electrical energy to the bus bars and through the conductive coating.