Electric lamp having an undercoat for increasing the light output of a luminescent layer
AssigneePhilips Electronics North America Corporation
InventorCharles Trushell
Life of this patent
Estimating the term…
Abstract
An electric lamp having a luminescent layer on the lamp envelope which produces visible light when impinged by ultraviolet radiation generated within the lamp. An undercoat for the luminescent layer increases the luminous efficacy of the lamp. The undercoat comprises an agglomerated particulate material of predominantly gamma alumina having a primary crystallite size of less than about 0.05 .mu.m. The undercoat is effective to increase the luminous efficacy of certain fluorescent lamps so that they meet the minimum efficacy requirements of the Energy Policy Act of 1992.
Claims20
An electric lamp, comprising:
- a. a lamp envelope having an inner surface;
- b. means within the lamp envelope for generating ultraviolet radiation;
- c. a layer of a luminescent material adjacent the inner surface of the lamp envelope for generating visible light when impinged by said ultraviolet radiation;
- and
- d. an other layer, between said inner surface of said lamp envelope and said layer of luminescent material, for reflecting ultraviolet radiation which has passed through said layer of luminescent material back into said luminescent material for increasing the visible light output of said luminescent material, said ultraviolet reflecting material comprising an agglomerated particulate material of predominantly gamma alumina having a primary crystallite size of less than about 0.05 .mu.m, said ultraviolet reflecting layer of predominantly gamma alumina having a weight/surface area of between about 0.15 mg/cm.sup.2 and about 0.30 mg/cm.sup.2.
A low pressure mercury vapor fluorescent lamp, comprising:
- a. a tubular, light transmissive lamp envelope having opposing sealed ends and an inner tubular surface;
- b. a filling of mercury and a rare gas;
- c. a pair of discharge electrodes each arranged at a respective sealed end of said lamp envelope;
- d. means for connecting said discharge electrodes to a source of electric potential outside of said lamp envelope, whereby during lamp operation a gas discharge is maintained between said discharge electrodes, which gas discharge emits ultraviolet radiation;
- e. a first, light transmissive and ultraviolet radiation reflecting layer disposed on said inner surface of said lamp envelope, said first layer comprising an agglomerated particulate material of predominantly gamma alumina having a primary crystallite size of about 0.01 .mu.m, said first layer of material having a weight/surface area of between about 0.15 mg/cm.sup.2 and about 0.3 mg/cm.sup.2 ;
- and
- f. a second, layer of luminescent material disposed on said first layer.
An electric lamp, comprising:
- a. a lamp envelope having an inner surface;
- b. means within the lamp envelope for generating ultraviolet radiation;
- c. a layer of a luminescent material adjacent the inner surface of the lamp envelope for generating visible light when impinged by said ultraviolet radiation;
- and
- d. an other layer, between said inner surface of said lamp envelope and said layer of luminescent material, for reflecting ultraviolet radiation which has passed through said layer of luminescent material back into said luminescent material for increasing the visible light output of said luminescent material, said ultraviolet reflecting material comprising an agglomerated particulate material having a primary crystallite size of less than about 0.05 .mu.m, and having a weight/ surface area of between about 0.15mg/cm.sup.2 and about 0.30 mg/cm.sup.2.
Dependencies are inferred from the claim text.