Penetration phosphors for display devices
AssigneeSperry Rand Corporation
InventorStanley F. Ignasiak
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Abstract
La.sub.2 O.sub.2 S particles are employed as a carrier host in conjunction with terbium activator ions in a cathodo-luminescent penetration phosphor composition for cathode ray display tubes. A thin layer of La.sub.2 O.sub.2 SO.sub.4 :Tb or La.sub.2 O.sub.2 SO.sub.4 :Tb,Eu is utilized to provide a barrier which must be penetrated by excitation electrons to produce green spectral emission from the particle thereby increasing the voltage-turn-on characteristic of the phosphor. Additionally, methods are disclosed for synthesizing the same in addition to an improved method for synthesizing a penetration phosphor particle comprising a core of La.sub.2 O.sub.2 S:Tb and a barrier layer of La.sub.2 O.sub.2 S:Tb,Eu.
Claims6
A cathodo-luminescent particle for use in an electron tube comprising:
- a central region consisting of La.sub.2 O.sub.2 S with Tb.sub.2 O.sub.2 S uniformly distributed therethrough which produces a green, narrow-bandwidth emission upon electron excitation thereof, and
- a peripheral region surrounding said central region and comprised of La.sub.2 O.sub.2 SO.sub.4 with a distribution of Tb.sub.2 O.sub.2 SO.sub.4 therethrough for providing a barrier layer with respect to said central region which must be penetrated by said electrons before substantial emission emanates from said central region and wherein the concentrations of Tb.sub.2 O.sub.2 S and Tb.sub.2 O.sub.2 SO.sub.4 are substantially smaller than the respective concentrations of La.sub.2 O.sub.2 S and La.sub.2 O.sub.2 SO.sub.4.
An electron tube including an evacuated envelope, a cathodo-luminescent screen therein, and means for exciting said screen within said envelope by electrons, said screen including cathodo-luminescent particles comprising:
- phosphor particles for producing red, narrow-bandwidth emission upon electron excitation thereof, and
- penetration phosphor particles uniformly combined with said red phosphor particles for producing green narrow-bandwidth emission when penetrated by higher energy electrons with respect to said red-emission phosphor particles and wherein each penetration phosphor particle includes a central region consisting of La.sub.2 O.sub.2 S with a uniform distribution of Tb.sub.2 O.sub.2 S therethrough for producing said green narrow-bandwidth transmission upon electron excitation thereof and further including a peripheral region surrounding said central region and comprised of La.sub.2 O.sub.2 SO.sub.4 and distributions of Tb.sub.2 O.sub.2 SO.sub.4 or Tb.sub.2 O.sub.2 SO.sub.4 and Eu.sub.2 O.sub.2 SO.sub.4 therethrough for forming an energy barrier layer which must be penetrated by said electrons for a green emission to emanate from said central region;
- and
- wherein the respective concentrations of Tb.sub.2 O.sub.2 S and Tb.sub.2 O.sub.2 SO.sub.4 or Tb.sub.2 O.sub.2 SO.sub.4 and Eu.sub.2 O.sub.2 SO.sub.4 are substantially smaller than the concentrations of La.sub.2 O.sub.2 S and La.sub.2 O.sub.2 SO.sub.4, respectively.
Dependencies are inferred from the claim text.