Browse Prior Art Database

Membrane Electrochromic Display Employing Porous Fibrous Electrode

IP.com Disclosure Number: IPCOM000085580D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 19K

Publishing Venue

IBM

Related People

Cuomo, JJ: AUTHOR [+2]

Abstract

It is known that the incorporation of ion selective membranes can be used in electrochemical display devices, for eliminating the development of color forming reactions at the counter electrode during the erasure cycle. Such problems are severe in those electrochromic systems which employ redox reactions, where ions are reduced at the cathode to form colored species and during erasure by reversal of the electrode voltages. The colored species are erased at the same electrode, but form at the new cathode or counter electrode.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Membrane Electrochromic Display Employing Porous Fibrous Electrode

It is known that the incorporation of ion selective membranes can be used in electrochemical display devices, for eliminating the development of color forming reactions at the counter electrode during the erasure cycle. Such problems are severe in those electrochromic systems which employ redox reactions, where ions are reduced at the cathode to form colored species and during erasure by reversal of the electrode voltages. The colored species are erased at the same electrode, but form at the new cathode or counter electrode.

It is also known that selective membranes made conductive by a suitable electrolyte but which do no transport the electrochromic ions, can be used to eliminate the back or counter electrode color forming reaction. However another problem associated with electrochromic displays becomes of primary importance.

This problem exhibits itself as a difference in writing and erasure times of considerable proportion. The problem results since during the writing process, those ions in the immediate neighborhood of the electrode are reduced (or oxidized depending upon the reaction employed) and diffuse away from the electrode. For erasure these ions (colored species) must diffuse back to the electrode for them to be oxidized (or reduced). The times involved in this latter diffusion can be very long compared to the writing.

Described is the use of a porous or fibrous electrode at which the colored species are formed. The distance between fibers being very small <20 mu. This electrode is saturated with a suitable electrochromic and then placed in contact with a suitable ion exchange membrane which is made conductive by saturating with a suitable electrolyte. The cell is then completed by contacting the other side of...