While designing the LED Display Systems with Red and Green color LEDs (10 each in two rows), I am facing problem that there occurs ghost images. Can someone help me in eliminating those, please.
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Eleminating ghost images
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I think you are scanning
I think you are scanning LEDs.
You need to switch off LEDs which are ON before switching on the next bank.
If problem persist, try introducing a small delay during which all LED banks are off at the time of switch over.
Improperly designed
Improperly designed LED-multiplexing circuits can create ghost images. Ghost images result when parasitic current flows through LEDs that are intended to be in an off state (i.e. no current flowing through them); this causes very faint illumination or ghosting. These ghost-image currents typically result from the discharging of stray capacitances associated with the large, common-LED anode-node tracks and the slightly forward-biased LEDs themselves.
Faint ghosting images from parasitic currents can occur when the multiplexing changes phases from MUX0-bar to MUX1-bar and vice versa. The effect is most pronounced when the LEDs on the multiplexed circuits are different colors (light wavelengths) and, hence, has significantly different voltage drops for a given current flow.
Eliminating Ghost-Image Currents
The ghost-image currents can be eliminated by providing a discharge path for the parasitic node capacitances and providing a time for the discharge to occur.
Thanks for your help