POWDER LAYER FORMING METHOD ONTO INNER FACE OF BULB

摘要

PURPOSE:To eliminate the powder layer removing process at the portion not requiring the powder layer, by covering the portion of the inner face of a bulb not requiring the powder layer with a grounded conductive shield surrounded with the insulator then blowing the charged powder into the bulb. CONSTITUTION:A glass bulb 1 for the outer tube of a mercury lamp applied with the pre-processing such as the coating of the surface with the charge prevention agent to lower the superficial resistance is secured by a grounded holder 2. Then a hollow tubular shield 4 having the outer face tightly contacting with the inner face of a bulb neck section 5 while having a grounded section 6 made of the conductive material and formed with an insulative shell 8 covering the outer-circumference of said section 6 is inserted into the neck section 5. Thereafter a nozzle 3 incoroporating a charger is inserted through the shield 4 into the bulb and the charged fluorescent powder is injected to be coated onto the inner face. Since the fluorescent material is not adhered to the inner face of the neck section, the wiping process can be eliminated.