PURPOSE: To provide a tubular bulb using a glass bulb protection film material desirable from a viewpoint of environment and cost.
CONSTITUTION: A protection film 7 of urethane resin or butadiene rubber material is formed on the external surface of a glass bulb 1. The urethane resin material or butadiene rubber material does not generate harmful gas at the time of burning treatment, and imposes no problem on environment and health. Also, the film 7 of the material has high ductility as well as high resistance against abrasion. Thus, the film 7 well withstands internal or external pressure and is capable of effectively preventing the scatter of broken glass pieces, thereby increasing safety for a human body and an article. Furthermore, the material prevents the clouding of glass called 'weathering' and has an effect of maintaining high luminous efficiency over a long term without any drop in light transmission factor.
TAMURA NOBUHIRO