Abstract A luminescent screen of a mean film thickness of 20 to 50 Mu to be provided on the inner surface of the face of a flying-spot cathode-ray tube, which is formed of a cerium-activated rareearth silicate phosphor having a mean particle diameter of 15 Mu or less prepared by calcining at least either one of yttrium oxide or gadolinium oxide, cerium oxide, silicon oxide, and 1 to 20 percent by weight of an alkali metal halide in air or under a reducing atmosphere at 900* to 1,300*C. When the luminous output from such a cathode-ray tube is utilized as an image signal after having been converted into an electric signal, it is possible to ensure a high signal-to-noise ratio between the signal and the noise from a photo-cathode in response to said luminous output incident to the photocathode.
A luminescent screen according to claim 1, wherein the mean particle diameter of the phosphor is 10 Mu or less.
Claim 2
Dependent Claim
21 words
A luminescent screen according to claim 1, wherein the mean film thickness of the phosphor is 30 to 35 Mu .
Claim 3
Dependent Claim
97 words
In a flying-spot cathode-ray tube having at least an electron gun and an envelope composed of a face, a funnel and a neck, the improvement in which there has on the inner surface of the face a luminescent screen of 20 to 50 Mu in mean film thickness composed of a cerium-activated rare-earth silicate phosphor having a mean particle diameter of 15 Mu or less, which has been prepared by calcining either one or both of yttrium oxide and gadolinium oxide, cerium oxide, silicon oxide, and 1 to 20 percent by weight of an alkali metal halide.
Claim 4
Dependent Claim
23 words
The improvement according to claim 4, wherein the mean film thickness of the phosphor of the screen is 30 to 35 Mu .