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Protection of Tungsten Oxide Electrochromic Displays

IP.com Disclosure Number: IPCOM000089811D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Barclay, DJ: AUTHOR [+2]

Abstract

Tungsten oxide (WO(3)) is widely proposed as the active material in an electrochromic display. It is, however, subject to dissolution in sulphuric acid, which is the preferred electrolyte. Evidence suggests that written WO(3), i.e., hydrogen bronze, is insoluble. To inhibit dissolution of WO(3) two methods of operating are proposed: (1) The display is maintained in the fully written state, and "writing" is effected by erasing hydrogen bronze until the contrastingly colored display electrode is revealed. To maintain charge equalization between written and unwritten electrodes, an invisible layer of tungsten bronze is retained on each electrode. This display results in white electrodes on a dark background.

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Protection of Tungsten Oxide Electrochromic Displays

Tungsten oxide (WO(3)) is widely proposed as the active material in an electrochromic display. It is, however, subject to dissolution in sulphuric acid, which is the preferred electrolyte. Evidence suggests that written WO(3), i.e., hydrogen bronze, is insoluble. To inhibit dissolution of WO(3) two methods of operating are proposed: (1) The display is maintained in the fully written state, and "writing" is effected by erasing hydrogen bronze until the contrastingly colored display electrode is revealed. To maintain charge equalization between written and unwritten electrodes, an invisible layer of tungsten bronze is retained on each electrode. This display results in white electrodes on a dark background. (2) An invisible layer of hydrogen bronze is maintained on each display electrode, and writing takes place on top of this layer. Dark electrodes against a light background result from this proposal.

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