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Phosphor Screen Precipitation Process

IP.com Disclosure Number: IPCOM000051685D
Original Publication Date: 1981-Feb-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Ludeke, R: AUTHOR

Abstract

Phosphor screens, which convert electron beams or short-wavelength lig into visible light, should be made not much thicker than the wavelength of the emitting light in order to improve image definition and efficiency by avoiding scattered light and self-absorption. Based on such criterion a thickness of 1 micrometer is generally more than sufficient since the penetration depth of the exciting radiation ~electrons or photons) is generally an order of magnitude smaller. A micro-precipitate of the phosphor is produced by dissolving to near saturation in a solvent and quickly diluting this solution with a second liquid, which is miscible with the solvent but does not dissolve the phosphor.

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Phosphor Screen Precipitation Process

Phosphor screens, which convert electron beams or short-wavelength lig into visible light, should be made not much thicker than the wavelength of the emitting light in order to improve image definition and efficiency by avoiding scattered light and self-absorption. Based on such criterion a thickness of 1 micrometer is generally more than sufficient since the penetration depth of the exciting radiation ~electrons or photons) is generally an order of magnitude smaller. A micro-precipitate of the phosphor is produced by dissolving to near saturation in a solvent and quickly diluting this solution with a second liquid, which is miscible with the solvent but does not dissolve the phosphor. The phosphor immediately comes out of solution into a very fine-grained precipitate which settles to the bottom if its gravity is sufficiently larger than that of the second liquid.

The phosphor sodium salicylate will produce film thicknesses of one micron by dissolving it in methyl alcohol and then quenching this solution with toluene. The mixture exhibits a slightly bluish tint indicating the presence of a fine grained precipitate which is allowed to settle. The toluene evaporates, leaving the precipitate evenly coated on the screen.

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