Patent ID: 7198850

Claim:
A glazing panel comprising a glass substrate coated with a film stacking arrangement comprising in sequence at least: a base antireflective layer comprising at least a base antireflective lower layer and a base antireflective upper layer which is of a different composition to that of the base antireflective lower layer, the base antireflective upper layer comprising a mixed oxide of Zn and at least one additional material X, in which the ratio X/Zn in the base antireflective upper layer is between 0.02 and 0.5 by weight and in which X is one or more of the materials selected from the group consisting of Sn, Al, Ga, In, Zr, Sb, Di, Mg, Nb, Ta and Ti; a first infra-red reflecting layer; a first barrier layer; a central antireflective layer comprising at least a central antireflective lower layer and a central antireflective upper layer which is of a different composition to that of the central antireflective lower layer, the central antireflective upper layer comprising a mixed oxide of Zn and at least one additional material Y, in which the ratio Y/Zn in the central antireflective upper layer is between 0.02 and 0.5 by weight and in which Y is one or more of the materials selected from the group consisting of Sn, Al, Ga, In, Zr, Sb, Bi, Mg, Nb, Ta and Ti; a second infra-red reflecting layer; a second barrier layer; and a top antireflective layer; the glazing panel further including at least one of the following features: (A) the glazing panel has an emissivity of less than 0.35 (B) the glazing panel has an electrical resistance of less than 3 ohms per square (C) the glazing panel, once laminated, has colour co-ordinates on the ClElab scale of L*=40±2.5 a*=−6±2.5 b*=−2±2.5 (D) the glazing panel, once laminated, has a luminous transmittance of at least 75% (E) the glazing panel, once laminated, has a variation of colour ΔE* over the surface of the glazing of less than 2 (F) the glazing panel has a haze, after heat treatment, not exceeding 0.3 (G) the glazing panel presents an absolute increase of luminous transmittance during heat treatment of at least 5%.