Pilkington Group Limited

Tobias Breil

Thomas Paul

Axel Nöthe

The present invention relates to a transparent substrate comprising a multiple layer coating stack and the use of same in the manufacture of a double glazing unit, wherein the multiple layer coating stack comprises, n functional metal layer, m; and n plus 1 (n+1) dielectric layer, d, wherein the dielectric layers are positioned before and after each functional metal layer, and wherein n is the total number of functional metal layer in the stack counted from the substrate and is greater than or equal to 3; and wherein each dielectric layer comprises one or more layers, characterized in that the geometrical layer thickness of each functional metal layer in the coating stack Gm, is greater than the geometrical layer thickness of each functional metal layer appearing before it in the multiple layer coating stack, that is, Gmi+1>Gmwherein i is the position of the functional metal layer in the coating stack counted from the substrate, and wherein for each dielectric layer d located before and after each functional metal layer m, the optical layer thickness of each dielectric layer (opln) is greater than or equal to the optical layer thickness of the dielectric layer (opln−1) positioned before it in the coating stack with the proviso that: twice the optical layer thickness of the first dielectric layer (opl) in the coating stack, is less than the optical layer thickness of the second dielectric layer (opl) in the coating stack, that is, (2×opl)<opl; and twice the optical layer thickness of the last dielectric layer (opl) in the coating stack, is greater than the thickness of the optical layer thickness of the penultimate dielectric layer (opl), that is, (opl)<(opl)×2.

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Dorsten, Germany

Tobias Breil