Browse Prior Art Database

Scannable Refresh Type Electrochromic Display

IP.com Disclosure Number: IPCOM000083091D
Original Publication Date: 1975-Mar-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Chang, IF: AUTHOR

Abstract

Electrochromic effect generally exhibits memory. However this memory results from accumulation of charge which appears as a back EMF when electrochromic color occurs. This back EMF makes matrix addressing difficult and inconvenient. There is described here refresh-type electrochromic display which is suitable for a matrix address. Basically, this is achieved by adding an oxidizing agent to the electrochromic material.

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Scannable Refresh Type Electrochromic Display

Electrochromic effect generally exhibits memory. However this memory results from accumulation of charge which appears as a back EMF when electrochromic color occurs. This back EMF makes matrix addressing difficult and inconvenient. There is described here refresh-type electrochromic display which is suitable for a matrix address. Basically, this is achieved by adding an oxidizing agent to the electrochromic material.

In general terms, the electrochromic effect, with added oxidizing agent, can be described as, Ox + ne --> Red (colored species) Red + O' --> Ox + O'' O'' - ne --> O'

The oxidizing agent O' is added to the redox pair Ox - Red, and acts to provide a regenerating mechanism for Ox. When a voltage pulse of one polarity is applied to the above-described system, Ox is reduced to a colored species Red, at a rate K(1). Red (species of color) is then oxidized by the oxidizing agent O' at a rate K , which may be adjusted by selecting different species of O' and its concentration with respect to the concentration of Ox.

The species O' is not consumed because it is replenished by oxidation at the opposite electrode, or by an opposite polarity pulse at the same electrode. One such example of oxidizing agent is H(2)O(2). Thus, H(2)O(2) + 2H/+/ + 2 Red --> 20x + 2H(2)O 2H(2)O - 2e --> H(2)O(2) + 2H/+/ where Ox-Red is a tungsten polyanion complex, i.e., Ox + e --> Red.

By including the regenerating chemical reaction in t...