PURPOSE: To suppress the luminous flux degradation during life by forming, on the inner surface of a glass bulb, a protective film mainly containing a rutile titanium dioxide fine particle the surface of which is coated with fine powder of zirconium oxide.
CONSTITUTION: On the inner surface of a glass bulb 1, a protective film 2 mainly containing granular rutile titanium dioxide fine particle having a recessed part or through hole, the surface of which is coated with fine powder of zirconium oxide and aluminium oxide, is formed. A phosphor layer 3 is provided on the layer 2. Thus, the characteristic in that luminous flux reduction is minimized through the life of a fluorescent lamp can be provided. Since the film 2 has no bad effect also on heating work and exhausting process in the manufacturing process of the fluorescent lamp, when it is applied particularly to a fluorescent lamp manufactured by the use of bridge bonding or bending work, the luminous flux degradation can be minimized through the life of such a fluorescent lamp.
KAWABATA ICHIRO
TAGUCHI YASUHIKO
KONDO EIJI
