Red emitting phosphor for cathode ray tube

Abstract

A red emitting phosphor comprises a yttrium oxysulfide phosphor as a base material. A red emitting phosphor of medium particle size type has such a particle size distribution that a content of a component of a particle diameter of less than 4.0 μm is 15% or less, that of a component of a particle diameter of 4.0 μm or more and less than 8.0 μm is 75% or more, and that of a component of a particle diameter of 8.0 μm or more is 10% or less. A red emitting phosphor of larger particle size type has such a particle size distribution that the content of a component of a particle diameter of less than 5.04 μm is 20% or less, that of a component of a particle diameter of 5.04 μm or more and less than 10.079 μm is 70% or more, and that of a component of a particle diameter of 10.079 μm or more is 10% or less. Phosphor layers employing these red emitting phosphors are excellent in denseness. Accordingly, a cathode ray tube of high contrast and high quality can be provided.

Dependencies are inferred from the claim text.