Patent GB-964508-A (GB)
Title: Luminescent panels
Inventor: MARZOCCHI ALFRED
IPC: H01J29/24
Filed: 1960-07-26
Abstract: A luminescent or electroluminescent panel, for use in building construction, comprises a sheet of resinous material, a multiplicity of elongated glass elements, in the form of flakes or fibres, embedded in the resinous material with their longer axes generally oriented towards a light-emitting surface of the sheet, and <FORM:0964508/C4-C5/1> within the confines of the sheet, an excitable phosphor, at least some of the glass elements extending to the light emitting surface of the sheet whereby light emanating from subsurface phosphor within the mass of the sheet is conducted by the glass elements to the surface of the sheet and emitted therefrom.  The phosphor can be a metallic sulphide such as zinc sulphide and the resinous material can be methyl methacrylate and other acrylics, regenerated cellulose, cellulose esters and ethers, epoxies or polyesters.  The glass elements can comprise up to 75% by weight of the phosphor containing resinous material.  A panel excitable by visible or ultra-violet light can be made by forming a sheet of the phosphor and glass containing resinous material with the glass elements oriented lengthwise in the sheet, slicing the sheet into sections in the direction of its thickness, rotating the sections through 90 degrees and joining them together to produce a panel with the glass elements substantially in the direction of the thickness of the sheet. Orientation of the glass elements can be effected by mechanically deforming the sheet during cure or by curing the sheet on a mould with projections set at an angle.  At least part of the phosphor can be on the surfaces of the glass elements or the phosphor can be contained at least in part within the glass elements, e.g. by being a constituent of the glass of which the glass elements are formed.  The glass elements can be leached prior to use to alter their light diffusing qualities and to provide irregularities for the reception of phosphor particles prior to incorporation in the resinous mass. The surfaces of the glass elements can be reduced in reflectivity by a fluoride coating thereon.  The light emitting surface of the panel can be at least in part grooved or prismatic. The glass elements can be made from fluorescent or thermoluminescent glasses and the coloured light therefrom added to the light from the phosphor or can form the sole light source.  The phosphor can be excited by radio-active radiation from radio-active substances coated on the glass elements such as atomic pile wastes, naturally occurring radium or synthetically produced barium or sodium isotopes. Alternatively, radio-active gas such as tritium or promethium, or heavy water, can be adsorbed on the surface of the glass elements. The panel is protected on each of its exposed surfaces by a transparent shielding layer of high density lead glass flakes and one surface can be metallized to form a mirror. In modifications radio-active material can be adsorbed on particles of silica gel which can be mixed with the resinous material or can be adhered to the surface of the glass elements, or the glass elements themselves can be radio-active by being made of uranium glasses formed from the oxide of U238 slightly enriched with U235.  Electroluminescent panels can contain a field responsive phosphor together with small quantities of electro-conductive material such as copper sulphide and can be formed by attracting the glass elements electrostatically to a charged plate, lowering the plate into a mould containing a mass of uncured, liquid, phosphor-bearing resin, and curing the resin. The above method can also be used with phosphors excited by ultra-violet light, the glass elements being made of quartz glass, and the resulting panel can form the ceiling of a room, a mercury vapour arc lamp being positioned behind the panel.  The panel can also be made by casting a thin film of the phosphor and glass element bearing resin on a flat surface and over a frame of thin parallel wires, and while the resin is still uncured withdrawing the frame vertically. In another method a glass pile fabtic is impregnated with the uncured phosphor bearing resin, the resin is cured and the warp and woof threads of the fabric removed.  The panel is covered on each of its top and bottom planar surfaces with a layer of horizontally oriented electrically conductive leached or frosted light diffusing glass elements.  A number of sheets so made can be formed into a sandwich construction as shown in Fig. 8, alternate ones 11A of the conductive layers being connected to one side of an A.C. or pulsating current source 12 and the remaining conductive layers 11B being connected to the other side thereof.