Understanding the Keypad circuit may help and boost your knowledge on fixing keypad problem issues on mobile phones. Keypads is a part of user interface being used to navigate or enter numbers, letters and characters, browse application, sends information and etc.
An schematic diagram below will help us understand how keypad circuits works and which components or parts did this circuit is being connected.
In this diagram the each and every key switching pads is being divided and grouped into rows and columns. Each rows and columns were group into 2 -5 keypads switch. This rows and columns have each corresponding lines according to each and every group of switching pads.
This lines of rows and columns is being filtered for EMI and ESD protection the EMI filter is made of tiny chip that used to protect such EMI and ESD interference.
this block diagram below shows how the switching signal is being triggered to process a command data.
flexible wire like those Slide Type package of mobile phones. Some flexible wires are very vulnerable and common cause of keypad malfunction.