Blackening of Inner Glass Surface in Fluorescent Lamps for LCD Backlight

The different degrees of blackening were observed at the inner surface of borosilicate, soda-lime, and aluminosilicate glass tubes having different sodium (Na) contents. The sodium contents () within the borosilicate, soda-lime, and aluminosilicate glass tubes were found to be 4%, 14%, and 0.06%, respectively. The degree of blackening was shown to increase as the sodium content within the glass of the fluorescent lamp containing Ne+Ar+Hg gas mixture. Higher degree of blackening was observed from the inner surface of the glass tube coated with . The blackening was found to be originated from the amalgam of generated by the chemical reaction between the mercury ions within the discharge gas and sodium within the glass tube during operation.