| 摘要 |
PROBLEM TO BE SOLVED: To effectively improve the brightness of the afterglow of a phosphor screen at the time of turning off power by forming a layer near a bulb mainly out of a long-persistence layer among the luminous layers made of a phosphor, and stacking an ordinary luminous layer on the long-persistence layer. SOLUTION: A reflecting layer 2 is formed on the inner surface of a bulb 1 at the prescribed angular aperture ofθand, therefore, light emitted from an aperture 2a is a synthesis of direct light from the first and second luminous layers 3 and 4, and reflected light emitted from the reflecting layer 2 through a reflection process. As a result, the brightness of the aperture 2a increases along a normal line, and an afterglow at the time of turning off power extends. In particular, the first luminous layer 3 is stacked on the reflecting layer 2, and has a sufficient amount of a long-persistence phosphor deposited. Thus, emitted light at the time of turning off power is discharged from the aperture 2a in a concentrated form, thereby providing a bright afterglow.
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