Electroluminescent LCD back iluminator

Go To Last Post
9 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I have an LCD display with an electroluminescent back light.
There is no illumination behind the LCD panel.
Testing the output of the high voltage inverter with illuminator connected show approximately 80Vac is present.
When there is no load the inverter produces approx 170VAC.

What are typical failure modes of these illuminators?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

We use EL lamps behind button panels. ERG makes EL inveters, and their app notes have good info. One can PWM the ground pin on the ERG inverters to dimm the HV AC. The lamp is a 'lossy capacitor' model. Needs a certain watts per square inch of area as per ERG appnote.

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

And with time, they still get dimmer and dimmer and dimmer and dimmer...

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

What a wonderfully plastic description; one can almost not see it in the end..much like the display.

Is there a way to rejuvenate and or replace / hack with a bunch of LEDS?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

We send em out with an LM317 and a trim pot. Turn it up as it gets dimmer.

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Presently the HV module is powered by a 7805 regulator.

What might be a suitable voltage across the EL module?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The EL lamp datasheet tells you. 5V into the ERG inverter gives 80, 100, 120 VAC at 400Hz depending on dash number. If you get a hold of the inverter out it will tingle from your fingers to your shoulder. It hurts. Be careful.

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thanks Bob,

I respect the extra low voltage delineation. (< 50V)

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Don't they use E.L. gauges in cars these days? How do they pull that off?