PURPOSE: To keep off any irregular reflection on a phosphor application surface of reflected light on the outgoing surface of a first lens and improve a contrast by regulating surface roughness at the phosphor application side of a face panel to the specified range.
CONSTITUTION: A surface state in an application surface of a phosphor 3 of a projection CRT face panel 2 is 0.1W1.0μm in maximum roughness, and this maximum roughness should be set to be less than 1/500 in crest pitch of a roughness curve. Light passed through a phosphor application surface passes by the phosphor 3 and fully reflected at a metalback 4, and it returns to the front again. An image so far seen on a screen comes out of sight due to irregular reflection on the phosphor application surface. The image by the irregular reflection on the application surface is left behind to the last around there and not going out of sight, but on the contrary, the image made by reflection at the application surface and the metalback will not appear on the screen because the reflected light is out of an effective beam passing range of a projecting lens, so that a contrast of the whole projected image can be raised.
MORI SHIGERU
HIRATA KOJI
MURANAKA MASAYUKI
MARUYAMA TAKESUKE
