Abstract: A mercury vapor discharge fluorescent lamp is provided having a single composite phosphor-containing layer. The composite layer contains both a heterogeneous mixture of halophosphors, rare earth triphosphors and colloidal alumina particles. The coating weight and relative proportion of halophosphors to triphosphors are both tunable to obtain a lamp having specific performance characteristics suitable to a particular application. The colloidal alumina particles contained in the composite layer eliminate the need for a separately applied alumina layer as is conventional in the prior art.

Abstract: A mercury vapor discharge lamp is provided having either a yttria-dispersed alumina barrier layer, or a yttria-dispersed phosphor layer with no barrier layer. The yttria-dispersed layer is preferably coated directly on the inner surface of the glass envelope of a fluorescent lamp, and substantially reduces mercury depletion via reaction with the glass envelope. Preferably, the yttria-dispersed layer also has a fine coating of yttria deposited over the surfaces of the coating particles, and over the inner surface of the glass envelope. A method of preparing a coating layer having such a yttria coating, and yttria particles uniformly dispersed therethrough, is also provided.

Abstract: A process for recovering rare-earth phosphors from an interior of a lamp envelope (12). The interior of the envelope defines a wall and a base layer (14) is adhered to the wall. A coating layer (16) having the rare-earth phosphors is adhered to the base layer. The process includes flowing a gas through the envelope at a rate sufficient to remove particles of the coating layer but not the base layer. The process also includes collecting the particles of the coating layer, the particles containing the rare-earth phosphors. Lamp envelopes (12) having a base layer (14) and a phosphor coating layer (16) suitable for use with the recycling method are also discussed.

Abstract: A reflector fluorescent lamp with a reflective layer between the light-transmissive envelope and the phosphor layer(s). The reflective layer has a coating weight of at least 5, more preferably 6-8, mg/cm.sup.2 and is a blend of gamma alumina and alpha alumina, preferably 7-80 weight percent gamma alumina and 20-93 weight percent alpha alumina, more preferably 30-40 weight percent gamma alumina and 60-70 weight percent alpha alumina. The reflective layer finds particular utility in an electrodeless fluorescent lamp.

Abstract: A fluorescent lamp with an ultraviolet reflecting barrier layer between the glass envelope and the phosphor layer(s). The barrier layer is a blend of gamma alumina and alpha alumina, preferably 5-80 weight percent gamma alumina and 20-95 weight percent alpha alumina. The barrier layer is effective to reflect UV light back into the phosphor layer(s), leading to improved phosphor utilization and more efficient production of visible light.

Abstract: A fluorescent lamp includes a non-conductive metal oxide layer which cooperates with an overlying starting aid conductive layer to increase the latter's electrical resistance adjacent the lamp electrodes in order to suppress the occurrence of appearance defects associated with mercury condensation. A method of making the lamp includes forming the non-conductive layer along end portions of an inner wall of the lamp glass tube adjacent the electrodes.

Abstract: Fluorescent lamps having a tin oxide layer protected by a layer of colloidal alumina having a median particle diameter below 0.4 micron exhibit an objectionable pearlescent coloration if the alumina layer thickness is within the range of 500-8,000 .ANG.. This coloration is reduced to an acceptable level by incorporating from 10-30 wt. % of particulate alumina having a median diameter above 0.75 micron in the colloidal alumina.

Abstract: Mercury condensation in dual phosphor layer fluorescent lamps is inhibited by mixing alumina particles having a median particle size not less than about one-half micron with the phosphor particles in the first phosphor layer which is disposed adjacent the inner lamp envelope surface.

Abstract: Method and apparatus for electrostatically applying phosphor coatings to the interior surface of fluorescent lamp tubes includes equipment for applying an electrical charge of one polarity to the glass wall and electrical charge of the opposite polarity to the phosphor particles to cause the phosphor particles to adhere to the glass surface until the particles can be heated to bond them to the interior surface of the glass by lehring. By using electrostatic deposition the lehring may be done at a lower temperature than is required with conventional phosphor deposition using organic binders so that U-shaped fluorescent lamps do not experience distortion from the lehring temperature. The invention includes the fluorescent lamps provided which are devoid of residue of organic binder.