Patent GB-997782-A (GB)
Title: Improvements in or relating to electroluminescent elements
IPC: H05B33/26
Filed: 1961-02-03
Abstract: <PICT:0997782/C1/1> <PICT:0997782/C1/2> A glass enamel contains not more than 17.5 mol. per cent of alkali metal oxide and can have the mol. percentage composition, Li2O-5, Na2O-10, CaO-6, SrO-4.5, ZnO-14.5, TiO2-3.5, Al2O-3.5, SiO2-23, B2O3-30.  In the device shown in Fig. 1 an electroluminescent device comprises a glass enamel layer 3 incorporating electroluminescent material and a metal carrier 1 therefor consisting of chrome-iron or of iron or an iron alloy having a chromium-rich surface zone adjacent the glass-enamel layer, a chromium oxide transition layer 2 being present on the carrier beneath the glass enamel layer, the glass enamel layer being disposed between conductive layers 1 and 4, and the conductive layer 4 on the side remote from the carrier being transparent.  The layer 4 can be of tin oxide covered with a glass layer 5. The carrier 1 can constitute one of the conductive layers and can consist of an alloy of 25% chromium and 75% iron by weight.  The glass enamel layer can have a thickness of from 20 to 80 microns and can be a composite layer 13, Fig. 2, built up of a first layer 14 adjacent the metal carrier 11 and containing titanium dioxide pigment and a second layer 15 remote from the metal carrier and containing the electroluminescent material.  The first layer can have a thickness of from 5 to 50 microns and a titanium dioxide pigment content of from 5 to 20% by volume.  The second layer can have a thickness of from 15 to 50 microns and an electroluminescent material content of from 20 to 50% by volume. The oxide layer between the chrome-iron carrier and the glass enamel layer can have a thickness not greater than 1 micron and the device can be made by degreasing the carrier in a carbon tetrachloride bath at room temperature, applying a glass enamel suspension, heating to 450 DEG  C. to remove organic constituents and rapidly heating the carrier to the enamelling temperature of 700 DEG C.  The carrier can be covered on all sides with a layer of a hydrolysed silicic acid ester having a thickness of from 400 <\>rA to 10,000 <\>rA.  Specification 997,783 is referred to.ALSO:<PICT:0997782/C4-C5/1> <PICT:0997782/C4-C5/2> An electroluminescent device comprises a glass enamel layer 3 incorporating electroluminescent material and a metal carrier 1 therefor consisting of chrome-iron or of iron or an iron alloy having a chromium-rich surface zone adjacent the glass enamel layer, a chromium oxide transition layer 2 being present on the carrier beneath the glass enamel layer, the glass enamel layer being disposed between conductive layers 1 and 4, and the conductive layer 4 on the side remote from the carrier being transparent.  The layer 4 can be of tin oxide and can be covered with a glass layer 5.  The metal carrier 1 can constitute one of the conductive layers and can consist of an alloy of 25% chromium and 75% iron by weight.  The glass enamel layer can have a thickness of from 20 to 80 microns and can be a composite layer 13, Fig. 2, built up of a first layer 14 adjacent the metal carrier 11 and containing titanium dioxide pigment, and a second layer 15 remote from the metal carrier and containing the electroluminescent material.  The first layer can have a thickness of from 5 to 50 microns and a titanium dioxide pigment content of from 5 to 20% by volume.  The second layer can have a thickness of from 15 to 50 microns and an electroluminescent material content of from 20 to 50% by volume.  The glass enamel can contain not more than 17.5 mol. per cent of alkali metal oxide and can have the mol. percentage composition, Li2O-5, Na2O-10, CaO-6, SrO-4.5, ZnO-14.5, TiO2-3.5, Al2O3-3.5, SiO2-23, B2O3-30.  The oxide layer between the chrome-iron carrier and the glass enamel layer can have a thickness not greater than 1 micron and the device can be made by degreasing the carrier in a carbon tetrachloride bath at room temperature, applying a glass enamel suspension, heating to 450 DEG  C. to remove organic constituents and rapidly heating the carrier to the enamelling temperature of 700 DEG  C.  The chrome-iron carrier can be covered on all sides with a layer of a hydrolysed silicic acid ester having a thickness of from 400 <\>rA to 10,000 <\>rA. The electroluminescent material can be zinc sulphide activated with copper, silver, gold or manganese and coactivated with aluminium or chlorine.  Thicknesses of the various layers are given.  Specification 997,783 is referred to.