LCD module contrast seem to be weak

I have bought an LCD module (192x64) and wired it and uploaded the sketch from the LCD library (Arduino Playground - GLCDks0108)

but something weird happens, I have noticed that the lower the text is, the more clear you can see it.

for example:

there are 2 places in which "testing" is written and in one place you can barely see it.


the lower the text is the more clear you see it

however everything seem to be ok with the splash screen, it is very dark in each pixel of the screen.

what can cause this problem?

If the splash screen is OK then perhaps it has something to do with your sketch. Can you post the code you used to create the lower image.

the rest of the program is like the example sketch that comes with the library, the only thing i changed is in the loop void:

void loop()
{
GLCD.ClearScreen();
for (int i =0;i<8;i++)
{
GLCD.CursorTo(0,i);
GLCD.Puts("testing");
}
}

removing the GLCD.ClearScreen(); seemed to help, but i still got a problem.

this is what happens when i tried to draw a line:

and thats what happens a few seconds later

void  loop(){   // run over and over again
GLCD.DrawLine(0,0,100,30,BLACK);
}

You are hammering the panel by writing the same data over and over. If you put a delay(1000) in your test code I think the dimming problem will disappear.

You need only write data to the panel when you want some part of the image to change.