EL backlighting for LCD displays looks warm and inviting, particularly a light blue or a white.
LED backlighting looks harsh and cheesy, particularly that diffused deep blue driven by a white LED with white pixels that seems really popular on various gear, now.
unfortunately the operating lifetime of common EL material is measured in thousands of hours vs. tens of thousands for LEDs. Wish there were something that looked as good with longer working life or maybe a different power supply/inverter scheme could extend it.
A display made from tiny incandescent filaments for pixels would look great but horribly power hungry/expensive/unreliable etc.
A while back I got my hands on a bunch of surplus LCD modules with the legit Hitachi Ur-controller on board and solder points for the backlight inverter, even. Not just a blob-on-board! With the reflective backing removed and some EL tape slid undernearth gosh they look the business!
Don't know when these were made, early 1990s probably?
On a sunny day (Tue, 19 Feb 2019 23:16:27 -0500) it happened bitrex wrote in :
Forget about LCDs if you have enough power, use OLED. I have one small blue OLED now running 21900 hours, slight burn in but not a problem for displaying text and graphics. LCDs only win in case you have enough environmental light and only nano amps available. Viewing angle of OLED is a trillion times better too. Small OLEDs are cheap.
VFD displays were some of the nicest IMO, particularly for alarm clocks. Yes, I built a Heathkit clock when I was a kid...
Funny you should mention filaments - back in the 70s, many petrol pumps moved over from using (earlier) dials and (later) solari type flip panels to a valve like tube with yellow-hot filaments in a 7 segment layout. These were not nixies, but definitely glowing wires.
Numitrons. This is a little thing I built for fun running a single Numitron tube from an 8 pin microprocessor, outputs BCD to a 74LS47 decoder. The power supply is the LiPo battery at right.
The boost converter I used falls down if you try to draw all that current when the filaments are cold so I run a little pre-heat routine that cycles the segments as a PWM signal to the boost chip's shutdown pin slowly ramps up the average output voltage. Works fine that way. (bug in code in this vid is what's causing some issues with the display tho)
OLED displays are very nice-looking, price seems to be coming down all the time. I'm building a design in small volume and want an attractive display I'll get some to test out.
Yeah LCDs wash out if you're off-angle, that annoying contrast adjust pin where you have to temp compensate it if it's used outside in a climate like mine, bleh!
One (or 2, depends on the context) isn't a bad hit rate on accuracy. :-)
Don't forget all those fuel pump displays at filling stations way back in the 1970s which used the (relatively cheap compared to the LED based) digital/alphanumeric filament displays with their 100,000 hour ratings.
Filament lifetimes are just a matter of operating temperature. Just because the lighting industry decided way back in the (1940s?)[1] to settle on the thousand hour average lifetime compromise between efficacy and lifetime rating (in Europe and the UK with the 220/240v GLS tungsten filament lamps - in the USA,they decided on the more efficacious 750 hour standard to go with their already more efficacious 120v filament lamps, a decision for which we owe a debt of gratitude for the global 60W 810lm standard that now defines the "60W 806lm LED equivalent lamp"[2]), doesn't mean we can't have indicator and instrumentation illumination lamps with 15 to 20 thousand hour life ratings or those incandescent filament displays used by 1970s era fuel pumps with their 50 to 100 thousand hour life ratings.
Incidentally, the same applies to indicator LED lamps and displays which can easily exceed their GLS cousins' 15 to 25 thousand hour ratings by an order or two of magnitude for essentially the same reason. :-)
[1] An action unfairly regarded as that of a cartel looking after its own selfish interests. The plain fact is, there are limits to just how much service life you can get, on the average, out of an incandescent filament lamp for a given voltage, wattage rating and efficacy.
If you want greater lamp life, you sacrifice efficacy. Just doubling lamp life rating will cost you more in electricity costs than the savings made in relamping costs in the domestic setting.
In the USA, a 750 hour lamp life was deemed the optimum between energy consumption and relamping costs in a domestic setting whilst in the UK and Europe, in spite of the more fragile 220/240 volt filaments which couldn't be run as hot as the 120v filaments used in America, they chose the nice round figure of 1000 hours, resulting in more expensive overall running costs per Lumen's worth of lighting.
[2] The "60W" 810lm LED GLS lamp is significantly brighter than a 60W
220/240 volt 1000 hour lamp being only slightly dimmer than a 75W 220/240
1000 hour lamp.
That's contrary to my experience of them. Not too surprising when you realise just how long a life rating the filaments have (some 50 to 100 thousand hours) which equates to anywhere from 5 to 11 years of 24/7 service.
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