Method of making an improved electroluminescent device

DETAILED DESCRIPTION OF THE INVENTION It has been found that electroluminescent lamps in which the phosphor particles are encapsulated by alumina exhibit an improved effectiveness when water is present.
Not only is brightness increased but longevity is extended beyond that of conventional systems.
That an electroluminescent device should include water is contrary to conventional wisdom.
The prior art is replete with warnings to the effect that water in all forms is to be avoided and the patent literature bears testimony to the efforts made to avoid the disadvantages attributed to water in electroluminescent cells.
Applicant does not profess to understand the basis for this surprising discovery but there is reason to believe that in this instance water improves conductivity and/or the capacitance of the electroluminescent cell by increasing the electrolytic properties of the system.
This result is believed due to the polarity of the water molecules which impart to the binder system a similar polarizing effect.
As a result it is believed that a concomitant increase in conductivity occurs including an improved flow of electrons between the electrodes so that the cell can provide light emissions of enhanced intensity.
Although the present invention envisions broadly the addition of water to electroluminescent systems this concept has particular application to systems in which the phosphor particles are encapsulated by alumina.
The device of this invention is physically constructed according to procedures which are known in the art and the dielectric or barium titanate layer is prepared by conventional means.
Specifically, the dielectric layer is formulated by admixing barium titanate solids with a suitable solvent as, for example glycol ethers, alkyl ketones and aromatic solvents.
Suitable glycol ethers include propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol butyl ether and the like.
Suitable alkyl ketones include ketones such as lower alkyl ketones including acetone, methyl ethyl ketone, ethyl ketone and methylisobutyl ketone and the like