Editing Electroluminescence (section)

==Practical implementations==
The most common electroluminescent (EL) devices are composed of either powder (primarily used in lighting applications) or [[thin film]]s (for information displays.)

=== Light-emitting capacitor (LEC) ===
[[File:NightLight.jpg|right|thumbnail|An electroluminescent [[nightlight]] in operation (uses 0.08&nbsp;W at 230&nbsp;V, and dates from 1960; lit diameter is 59&nbsp;mm)]]
''Light-emitting capacitor'', or '''LEC''', is a term used since at least 1961<ref>''Proceedings of the National Electronics Conference, Volume 17'', National Engineering Conference, Inc., 1961;  page 328</ref> to describe electroluminescent panels. [[General Electric]] has patents dating to 1938 on flat electroluminescent panels that are still made as [[night light]]s and backlights for [[Control panel (engineering)|instrument panel]] displays. Electroluminescent panels are a [[capacitor]] where the [[dielectric]] between the outside plates is a [[phosphor]] that gives off [[photon]]s when the capacitor is charged.  By making one of the contacts transparent, the large area exposed emits light.<ref>Raymond Kane, Heinz Sell, ''Revolution in lamps: a chronicle of 50 years of progress, 2nd ed.'', The Fairmont Press, Inc., 2001 {{ISBN|0881733784}},  pages 122–124</ref>

Electroluminescent automotive instrument panel backlighting, with each gauge pointer also an individual light source, entered production on 1960 Chrysler and Imperial passenger cars, and was continued successfully on several Chrysler vehicles through 1967 and marketed as "Panelescent Lighting".

=== Night lights ===
The Sylvania Lighting Division in Salem and [[Danvers, Massachusetts]], produced and marketed an EL night light, under the trade name ''Panelescent'' at roughly the same time that the Chrysler instrument panels entered production. These lamps have proven extremely reliable, with some samples known to be still functional after nearly 50 years of continuous operation.{{when|date=March 2023}}

Later in the 1960s, Sylvania's Electronic Systems Division in [[Needham, Massachusetts]] developed and manufactured several instruments for the [[Apollo Lunar Module]] and [[Apollo Command Module|Command Module]] using [[electroluminescent display]] panels manufactured by the Electronic Tube Division of Sylvania at [[Emporium, Pennsylvania]]. [[Raytheon]] in [[Sudbury, Massachusetts]]  manufactured the [[Apollo Guidance Computer]], which used a Sylvania electroluminescent display panel as part of its display-keyboard interface ([[DSKY]]).

=== Display backlighting ===
[[File: Casio W-86 digital watch electroluminescent backlight (ii).jpg|thumb|A Casio digital LCD watch with an electroluminescent backlight]]
Powder phosphor-based electroluminescent panels are frequently used as backlights for [[liquid crystal display]]s. They readily provide gentle, even illumination for the entire display while consuming relatively little electric power. This makes them convenient for battery-operated devices such as pagers, wristwatches, and computer-controlled thermostats, and their gentle green-cyan glow is common in the technological world.

EL backlights require relatively high voltage (between 60 and 600 volts).<ref name=Handbook>Donald G. Fink and H. Wayne Beaty, ''Standard Handbook for Electrical Engineers, Eleventh Edition'', McGraw-Hill, New York, 1978, {{ISBN|0-07-020974-X}}  pp 22-28</ref> For battery-operated devices, this voltage must be generated by a [[boost converter]] circuit within the device. This converter often makes a faintly audible whine or siren sound while the backlight is activated. Line-voltage-operated devices may be activated directly from the power line; some electroluminescent nightlights operate in this fashion. Brightness per unit area increases with increased voltage and frequency.<ref name=Handbook/>

Thin-film phosphor electroluminescence was first commercialized during the 1980s by [[Sharp Corporation]] in Japan, [[Finlux]] (Oy Lohja Ab) in Finland, and [[Planar Systems]] in the US.  In these devices, bright, long-life light emission is achieved in thin-film yellow-emitting manganese-doped [[zinc sulfide]] material.  Displays using this technology were manufactured for medical and vehicle applications where ruggedness and wide viewing angles were crucial, and liquid crystal displays were not well developed. In 1992, [[Timex Group USA|Timex]] introduced its [[Indiglo]] EL display on some watches.

Recently,{{when|date=March 2023}} blue-, red-, and green-emitting thin film electroluminescent materials that offer the potential for long life and full-color electroluminescent displays have been developed.

The EL material must be enclosed between two electrodes and at least one electrode must be transparent to allow the escape of the produced light. Glass coated with [[indium tin oxide]] is commonly used as the front (transparent) electrode, while the back electrode is coated with reflective metal.  Additionally, other transparent conducting materials, such as [[carbon nanotube]] coatings or [[PEDOT]] can be used as the front electrode.

The display applications are primarily passive (i.e., voltages are driven from the edge of the display cf. driven from a transistor on the display). Similar to LCD trends, there have also been Active Matrix EL (AMEL) displays demonstrated, where the circuitry is added to prolong voltages at each pixel.  The solid-state nature of TFEL allows for a very rugged and high-resolution display fabricated even on silicon substrates.  AMEL displays of 1280×1024 at over 1000 lines per inch (LPI) have been demonstrated by a consortium including Planar Systems.<ref>Ron Khormaei, et al., "High-Resolution Active Matrix Electroluminescent Display", Society for Information Display Digest, p. 137, 1994.</ref><ref>{{Cite web|url=http://www.planar.com/support/design-resources/docs/overview.pdf |title=Active Matrix Electroluminescence (AMEL) |url-status=dead |archive-url=https://web.archive.org/web/20120722221137/http://www.planar.com/support/design-resources/docs/overview.pdf |archive-date=2012-07-22 }}</ref>