What is meaning by DEBOUNCE time. Why we have consider the optocoupler Fall time and Rise time during debounce time calculation.

 

De-bounce is usually applied to switches, to prevent them from giving false pulses when closing or opening, use a de-bounce circuit to eliminate the problem.

The time delay is due to the extra capacitance in the circuit.

http://www.google.co.uk/imgres?imgu...BYeR0AXhnoDIAQ&sqi=2&ved=0CDMQ9QEwAw&dur=4936

 

An average bounce time from imperfect memory is around 15 ms, so I use 20 ms to be on safe side. If a 1 ms 555 one shot is triggered with a switch, the output may consist of several 1 ms pulses; but if timing is increased to 20 ms the OS will not re trigger & only a single pulse will be outyputted. One form of debouncing.