# lcd signals.........

Discussion in 'General Electronics Discussion' started by stranger, Jun 20, 2010.

1. ### stranger

3
0
Jun 18, 2010
im working on decoding lcd signals.........where i read in the signals into a micro and find the digit the lcd display shows..........

I just wanted to know whether the signals are like..........one type of continuous signal for a one digit(like a different signal for 1 and 2) or if the signal is time dependent to produce a digit(like same signals for 1 and 2 but for different time intervals)......

2. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,490
2,831
Jan 21, 2010
LCD panels typically place an AC voltage across each segment or pixel. You'll find that the backplane has a square wave signal imposed on it. The segments that are off have the same signal, and the ones that are on have it inverted.

So, you'll see pretty much exactly the same signal (wrt gnd) on segments that are on or off. You need to compare the signal to the backplane and probably deglitch it.

3. ### Resqueline

2,848
2
Jul 31, 2009
And to add to the complexity; many small LCD's have the backplane divided into two, one for four of the segments and one for three of the segments + decimal points..