REFLECTOR, LIGHT SOURCE DEVICE, LIQUID CRYSTAL PROJECTOR, AND METHOD FOR DEPOSITING REFLECTING FILM COATINGS
A reflector having a reflecting film coating which is composed of a reduced number of deposition materials and has high resistance to heat, a light source device deposited with such a reflecting film coating, a liquid crystal projector adopting such a light source device, and a method for depositing such a reflecting film coating. The reflector is in the form of a multi-layer reflecting film coating having a low refractive film layer of silicon dioxide laminated alternately with a high refractive film layer of a mixed deposition material containing silicon dioxide along with at least one of high refractive deposition materials such as niobium oxide, tantalum oxide, titanium oxide and zirconium oxide. In forming a high refractive film layer, silicon dioxide, a low refractive deposition material, is mixed into a high refractive deposition material to prevent crystallization of the latter under heated conditions.
1 . A reflector in the form of a multi-layer reflecting film coating having a low refractive film layer of silicon dioxide laminated alternately with a high refractive film layer of a mixed deposition material containing silicon dioxide along with at least one of niobium oxide, tantalum oxide, titanium oxide and zirconium oxide.
2 . A reflector as defined in claim 1 , wherein high refractive film layers of said reflecting film coating contain silicon dioxide at a rate in a range of between 10% and 50%.
3 . A light source device comprising an incandescent source lamp, a reflector for condensing light emitted by said source lamp, and a multi-layer reflecting film coating deposited on said lamp, characterized in that:
said multi-layer reflecting film coating has a low refractive film layer of silicon dioxide laminated alternately with a high refractive film layer of a mixed deposition material containing silicon dioxide along with at least one of niobium oxide, tantalum oxide, titanium oxide and zirconium oxide.
4 . A liquid crystal projector comprising a light source device as set forth in claim 3 , liquid crystal display devices for modulating light from said light source, and an optical projection system for projecting light images on a screen.
5 . A method for depositing a multi-layer reflecting film coating having alternately a low refractive film layer of silicon dioxide and a high refractive film layer of a mixed deposition material containing silicon dioxide along with at least one of niobium oxide, tantalum oxide, titanium oxide and zirconium oxide, characterized in that said method comprises the steps of:
forming a low refractive film layer on a substrate by depositing vapors from an evaporation source of a low refractive deposition material; and
forming a high refractive film layer on said substrate by simultaneously depositing vapors from an evaporation source of a high refractive deposition material and vapors from said evaporation source of said low refractive deposition material;
repeating deposition of said low refractive film layer alternately with deposition of said high refractive film layer for a predetermined number of times.
6 . A method for depositing a multi-layer reflecting film coating as defined in claim 5 , wherein said low and high refractive film layers are deposited by vacuum deposition, ion plating or sputtering.