On the Rerations between the Thickness of the Fluorescent Powder Layer and the Brightness of the Reflector Type Fluorescent Lamp

The brightness of the reflector-type fluorescent lamp has been theoretically investigated with respect to the thickness of the fluorescent powder layer coating the inside wall of the tube, using the same method as described in the previous paper. The effects of the reflectance of the reflector coating on interreflection in the tube have been considered in the calculation. The effects of the thickness of the fluorescent powder layer on the light output of the tube have been obtained by theoretical investigation and it has been found that the proper thickness of the fluorescent powder layer for the reflector type fluorescent lampis slightly smaller than for the normal fluorescent lamp. Also, by varying the angle taken up by the fluorescent powder alone, it was found that a maximum luminous intensity in the preferred direction occurs when this angle is approximately 130°.