JPS6490288A - Fluorescent lamp - Google Patents

Abstract

PURPOSE:To prepare a phosphor lamp having high color rendering without use of Ge element at a low cost, by applying a phosphor film comprising a mixture of particular four kind of phosphorus to the internal surface of a glass tube. CONSTITUTION:If necessary, a fading preventive film 13 comprising a substance having capability of absorbing an ultraviolet ray and transmitting or reflecting a visible ray, such as TiO2 or Ce2O3 is formed on the internal surface of a glass tube 12. On the fading preventive film is applied a phosphor film 14 com prising a mixture of a first phosphor having a peak wavelength of 470-500nm in an emission spectrum and composed of an Eu<2+>-activated alkaline earth metal halophosphate of the formula [wherein M comprises Ba, Ca, and Mg, and when M is (Baa, Cab, Mgc), 3.0<=a(5-y)<=4.5, 0.5<=b(5-y)<=2.0, 0.01<=c(5-y)<=1.0, a+b+c=1, and 0.01<y<=0.20; and X is F, Cl or Br] with a second phosphor composed of the above ingredients and having a peak wavelength of 620-640nm and a half-value width of 120-160nm, a third phosphor composed of an Sb- activated calcium halophosphate, and a fourth phosphor composed of an Sb- and Mn-activated calcium halophosphate, thereby preparing fluorescent lamp 11.