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Crosstalk on QVGA LC-Display

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mr_ghz

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I use a b/w LC-Display QVGA size (320*240 pixels). To achive grayscales I use a frame rate modulation. The Framerate is 75Hz. Now there are two problems (not only with this configuration, they are common with this kind of LCD):
- I have crosstalk on the screen. If I have a white background and a dark box of about 80 by 80 pixels in the middle of the screen, i have lines (shadows) in the background area.
- The frame rate modulation gives stripes in the picture that moves. These effects are best visible in grayscales.
I know WHY these effects occur, but I'm looking for possibilities to minimize them. One idea I have is to rise the frame rate (but this is not within specification of manufacturer) this could give less 'stripes'. I heard something about modulating the driving voltage.
Has anyone other ideas, suggestions, ... ?

Bye
 

prd

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I'm not sure, what signal & power need in your LCD Panel interface connector.

If there need bias supply. Check the bias supply ratio. Also check that you have minimize supply impedance to all bias input. LCD manufacturer should show the method.

In my understand, modulating driving voltage, should do by LCD driver. If the LCD Panel have driver built-in, I think hard to change the modulating voltage format. The one you can try is high-volt supply.

Bye
prd
 

mr_ghz

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Hi there,

the problems (stripes and crosstalk) are not given through the digital interface. they are effects inside the lcd-glass. The 'stripes' in framerate modulation are produced by the low frame-rate. The crosstalk is given by quality problems of the lcd line- and column-drivers.
My interface is based on the 4-Bit bus before the line- and columndrivers. The same problems also exists with a eval-board, different glasses (more or less intensive).
Any ideas?
 

jacneo

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Maybe check the panel design.
look at data line width and top metal distance.
the couple capacitor will effect the crosstalk issue.
 

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