Ghost effect on Custom LCD

[longliveboy]

Hi everybody;

I'm working on a LCD but there is a ghost effect on passive segments. on the other hand when i change viewing angle all segmets appears.

IC is LL64

lcd frequency is 64Hz also lcd capacitance is 35800pF.

This values are so far away that LL16 support but i wanna know ghost effect causes from which conflict? 

[BasePointer]

For ghost effect: try reducing refresh rate to 30Hz.

For "all segmets appears": try reducing contrast and use lowest bias mode possible, for example 1/3 bias mode. 1/2 bias mode is bad at contast ratio.

[longliveboy]

Hi BasePointer;

i already try all freaquency ranges but result is same.

bias is fix at 1/3

do u know is TN lcds are couses this problem.

i know tn's viewing angle is too narrow but cant guess that it is as bad as mine.

already thanks

[BasePointer]

Hi,

Yes also low quality TN glasses can cause this problem. Try contacting your custom LCD manufacturer and ask for LCD parameters. We did many sample requests from the manufacturer in the past to find perfect lcd solution that has TN glass.

Also dont forget, multiplexing reduces total required pin count but it reduces contrast ratio too. We are using 4x40 = 160 segments custom LCD and TN glass without problem. (no ghost effect, wide range viewing angle) We need totally 44 pins. We could also choose 8x20 (28 pins) = 160 segments LCD but, it would have worse contrast ratio.

If you don't have price, industrial temperature range and life time problems, you can choose HTN or STN glass types.

BP.