Phantom Key Detection/Phantom Key Scan Code
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
To prevent keyboard malfunction in matrix-type keyboards, a technique is devised whereby if two or more keys are depressed simultaneously in the same matrix drive row, the keyboard processor will go into phantom detection mode. Therefore, any additional keys depressed in the same column as those keys in the phantom detection row will be ignored and a phantom key scan code is transmitted to the system unit indicating that a phantom key combination has occurred.