Mirrors with highly reflecting coatings, deposition of plural reflecting coatings on hot glass

摘要

A method of producing mirrors comprising depositing onto a ribbon of hot glass during the production process a coating comprising a reflecting layer and at least two reflection enhancing layers whereby the mirrors have a visible light reflection of at least 70%. In a preferred embodiment the coating-comprises: an inner layer having a refractive index of at least 1.6; an intermediate layer of relatively low refractive index and; an outer-layer having a refractive index of at least 1.6; the intermediate layer having a refractive index less than the refractive index of either said inner layer or said outer layer and less than 3, provided that at least one of said inner and outer layers is of silicon, the aggregate refractive index of the inner and outer layers is at least 5.5, and the thicknesses of the layers are such that the mirror has a visible light reflection of at least 70%. In an alternative embodiment, one of the inner and outer layers may instead be composed of a low refractive index reflective metal such as Al, Cr, Co, Ti and B or Ge may be used as an alternative to Si. Alternatively both layers may be formed of silicon, which may be formed by CVD or by pyrolysis of a liquid, or when only one is silicon the other may be formed from TaO2, TiO2, SnO2 or silicon oxides which may contain additional elements, eg nitrogen or carbon. The intermediate layer may be formed of silicon oxide which again may contain nitrogen or carbon. The reflecting layer may be the inner layer or the outer layer. A protective or an opaque layer may also be applied.