Phosphor, lamp and method

Claim 1

A FLUORESCENT LAMP COMPRISING A LIGHT-TRANSMITTING ENVELOPE HAVING ELECTRODES OPERATIVELY DISPOSED THEREIN AND CONTAINING AN INERT IONIZABLE GAS AND A CHARGE OF MERCURY, A HALOPHOSPHATE PHOSPHOR COATING ON THE INNER SURFACE OF SAID ENVELOPE, SAID PHOSPHOR HAVING BEEN PROCESSED AFTER FORMATION BY FIRING AND BEFORE LAMP ENVELOPE COATING BY THE METHOD COMPRISING, FINELY DIVIDING FIRED HALOPHOSPHATE PHOSPHOR SO THAT SUBSTANTIALLY ALL RESULTING PHOSPHOR PARTICLES HAVE A DIAMETER LESS THAN A PREDETERMINED VALUE, MIXING THE FINELY-DIVIDED PHOSPHOR AND AN AQUEOUS ACID SOLUTION, SEPARATING THE PHOSPHOR FROM THE AQUEOUS ACID SOLUTION, REMOVING SUBSTANTIALLY ALL RESIDUAL ACID FROM THE PHOSPHOR, FORMING A WATER SLURRY OF THE FINELY-DIVIDED PHOSPHOR, ATOMIZING THE PHOSPHOR-WATER SLURRY IN A GASEOUS MEDIUM HEATED TO A TEMPERATURE APPRECIABLY GREATER THAN THE BOILING POINT OF WATER AND LESS THAN THE FIRING TEMPERATURE USED IN MAKING THE PHOSPHOR TO EVAPORATE INTO THE HOT GASEOUS MEDIUM THE WATER COMPONENT OF THE ATOMIZED SLURRY, SEPARATING AT LEAST A SUBSTANTIAL PORTION OF THE DRIED FINELY-DIVIDED PHOSPHOR FROM THE HOT GASEOUS MEDIUM CONTAINING THE EVAPORATED WATER OF THE SLURRY, AND THEREAFTER STIRRING THE DRIED AND SEPARATED FINELY-DIVIDED PHOSPHOR TOGETHER WITH A VOLATILE VEHICLE AND A SMALL AMOUNT OF VEHICLESOLUBLE BINDER TO FORM A PHOSPHOR-VEHICLE SUSPENSION SUITABLE FOR PHOSPHOR COATING A FLUORESCENT LAMP ENVELOPE.