Computer keyboard is a device used to convert the keystrokes in to the electrical signals that a computer can understand. There are special types of switches and circuits to do this.When we press a key, it completes its corresponding circuit and an electrical signal goes to keyboard’s internal processor which detects the key which is pressed.A keyboard works on a 5V power which it takes from the computer through the Serial cable or USB. When we press a key on the keyboard, it pushes down the dome shaped rubber button which in turn electrically connects the top & bottom layer at that point and the signal is sent to the COB IC.