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Driving an EL backlight on a character LCD
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Driving an EL backlight on a character LCD

by nezb on Wed Nov 10, 2010 8:38 pm

Hi,

I recently got a 16x2 character LCD (not the one on the Adafruit store) and from what I gathered through research online it has an EL driven backlight as opposed to the more common LED backlight (I could be wrong though). I have no problems making text appear on the LCD from a microcontroller using 3.3V logic levels, but if someone could help me figure out how to drive the backlight I would be really happy as I don't know that much about the circuity required to do this.

I have captured high-res photos of it and the model printed on the PCB says "GEB 2294V O". Unfortunately I can't seem to find any datasheets on google. The pinouts on the bottom are irrelevant since the backlight is attached to the 2 wires & mini connector on the back, but if it helps: (pin1) Gnd, Vcc, Vee(contrast), RS(register select), R/W, E(clock), D4, D5, D6, D7 (pin10)

Thanks! :D

IMG_20101110_192557.jpg
lcd front
IMG_20101110_192557.jpg (986.66 KiB) Viewed 1805 times

IMG_20101110_192628.jpg
lcd back
IMG_20101110_192628.jpg (1009.26 KiB) Viewed 1805 times
nezb
 

Re: Driving an EL backlight on a character LCD

by westfw on Wed Nov 10, 2010 11:52 pm

EL backlights require moderately high voltage AC (typically 80V at 400Hz or so), usually provided by a fancy dedicated driver chip. The easy solution would probably be to buy one of the inverted aimed at EL case mods or EL wire (http://www.coolight.com/category-s/27.htm ) (but there goes your cheap display.)

westfw
 
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Re: Driving an EL backlight on a character LCD

by nezb on Fri Nov 12, 2010 1:15 pm

Hmm, it seems it will be more worth my time to just get another 16x2 LCD with LED backlight to replace this one. However, I did find what seems to be a very useful tutorial for EL backlight. Link: http://www.nerdkits.com/videos/backlight/

Also I managed to find a datasheet for this display: it is a Densitron LM2022! As it may be useful for someone else browsing the forum, the suggested spec for the backlight AC inverter is:
backlight.GIF
backlight specs
backlight.GIF (10.1 KiB) Viewed 1757 times
nezb
 

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