Browse Prior Art Database

Ion-Depletion Display Technology

IP.com Disclosure Number: IPCOM000040279D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Hoffman, HS: AUTHOR

Abstract

This article describes a display provided by an array of cells, the index of refraction of which is varied by selective application of electric fields. This display employs a variation of the long known Christiansen Effect, which historically uses temperature changes to alter the index of refraction. If small solid transparent particles are immersed in a fluid having a matching index of refraction, the particles do not scatter light which is passing through. For a particular wavelength, a change in index of the solution relative to the particles can cause scattering as a result of refraction. To enable use of this phenomenon to provide the information display described in this article, the effect is achieved by the use of the electric field applied to the solution.

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Ion-Depletion Display Technology

This article describes a display provided by an array of cells, the index of refraction of which is varied by selective application of electric fields. This display employs a variation of the long known Christiansen Effect, which historically uses temperature changes to alter the index of refraction. If small solid transparent particles are immersed in a fluid having a matching index of refraction, the particles do not scatter light which is passing through. For a particular wavelength, a change in index of the solution relative to the particles can cause scattering as a result of refraction. To enable use of this phenomenon to provide the information display described in this article, the effect is achieved by the use of the electric field applied to the solution. The index of refraction of a solution depends, among other factors such as temperature, upon the concentration. If the solution is ionic, then an electrostatic field can separate the ions and, more importantly, collect them as a wall charge on a dielectric. This depletes the concentration of the solute in the bulk of the solution. Nullification of the field can return the solution to its original concentrations. The figure illustrates the basic principle. The change of index of the solution in cells 10, 12 can cause a change in the critical angle 14 for total internal reflection at the interface between the fluid in 10, 12 and an edge-lit solid transparent plate 16 of h...