|
|
 |
|
 |
 Discussion
Topics List
Reply
To Topic | Search
Topics
| Author |
Topic |
1
Post |
Posted
13/7/2005
I bought a 16x2 character LCD (with backlighting) from Jaycar a week ago, and while the controller programming is finished, I've been having some issues with the backlighting.
Basically the backlighting comes on when the Anode and Cathode pins aren't even connected, but the LCD's controller power pins are connected. This makes me think that the A/K pins are there simply for "control" or switching the light on and off.
I was just wondering if I could possibly damage the LCD in anyway if I simply ground the anode when I want to turn off the backlight?
|
1
Post |
Posted
13/7/2005
You may find this is due to the internal protection diodes within the device. I’m not sure of the rating of these diodes but you may find it is close to or even exceeding the current requirements of the backlight so it’s possible this may cause damage.
My suggestion would be to supply the desired backlight voltage/current from a source capable of driving this. If you don’t want/need the backlight then connect both lines to ground.
|
Jay Cee
339
Posts |
Posted
16/7/2005
The back lighting for the lcd panel usually uses an electroluminescent panel, which requires around 90 volts ac to run,and is usually supplied by a small inverter, but why the el panel is glowing i can only guess, it may be due to a static build up, or, as it is basically a phosphorus compound it may be just fluorescing from a high amount of ambient light, but i am only guessing, so as the previous poster said, if you do not want the backlight, short the two el leads out and or to ground, also i would be checking the supply voltage to the lcd panel, if this is to high, not only will it damage the panel, it can cause the effect you have got now.
Come back if you need any more help.
Jay Cee
|
John Simpson
13
Posts |
Posted
2/2/2006
I have found the same issue with the Jaycar LCD modules. They power the LED backlight from the power supply that runs the panel. If you dont want to use the backlight, it looks like you can permanently turn it off by removing the 9R1 (R12) surface mount resistor in the top left hand corner on the back. If you then want to turn it on via your micro, you could solder a wire onto the "A" pad and run that to your micro via a 9.1 ohm resistor.
John.
|
| |
|
|
|
|
|
LCD's Backlighting.