EL vs AMLCD
Here is an update on our view of the AMLCD and EL capabilities. AMLCD's continue to improve in performance and cost as the consumer applications like TV drive high volumes. Plasma has driven significant improvements in video speed and brightness of AMLCD. These technology improvements also filter down to the industrial segment portfolios of the AMLCD manufacturers.
Even as these improvement are implemented, Thin-film EL displays still out-perform AMLCD's in a number of categories and likely will always do so due to fundamental differences in the technologies.
Planar manufactures a number of EL displays with -40 to +85C specs for operating temperature range. The yellow phosphor in EL are inorganic (ZnS doped with Manganese). They don't freeze or get get slow or dim even at low temperatures. The EL panel itself is quite happy to function at temperatures well below -55C. Any display temperature limitation is typically due to the interconnects to the panel or the power supply electronics where AE caps give up (ESR goes to crap when they freeze) and need to be enhanced with ceramics or circuits need to spiffed up to handle higher ripple voltages. Also at the low temp end EL does not suffer from the poor light output and difficulties in starting that typical CCFL lamps in AMLCDs have to suffer.
At the high temp end, EL has no issues like AMLCD clearing point that prevents the display from functioning under sunlight loading or simply high temperatures in an enclosure that is not cooled in outdoor or industrial situations. AMLCDs with CCFL lamps also suffer brightness degradation as the CCFL lamps get hot. Their efficiency is really peaky around room temp.
So how about those new industrial AMLCD displays with LED backlights? Well they seem to solve the CCFL light source problem at low temps (instant turn-on, better reliability) but you still have the problem on the liquid crystal material turning to gelatin getting, oh, so painfully slow... And at the high temp end now they AMLCD manufacturers have another problem. In order to get decent brightness from the display (and keep the LED cost under control) you have to drive the heck out the LEDs. This translates to high die temps and lifetime issues if you go too far, so the high temp specs are still limited. And the bright white LED's also have some brightness life issues when driven too hard as well.
EL also "lasts a life-time." The panel itself has no significant wearout mechanism. Unlike the CCFL typically used in AMLCDs Planar has never seen a "50% brightness" EL display....
Since EL is a light emitting display technology with no optical elements in the light path (other than the glass substrate) viewing angle is typically limited by the user's bezel blocking pixels before the display itself has any issues. This is one of the characteristics that has made EL so popular in the Medical arena for EMS services. EMT's can throw the monitor or defibrillator on the pavement and if they can see the display they can read the information displayed.
It's high contrast also gives EL what we call "at a glance" readability. Anywhere where the information has high value when conveyed in near real time EL beats out AMLCD if full color is not a must.