Patent ID: 9513325
Filing Date: 2016-12-06
CPC Classification: G01R,G06F,H03M

Claim Text:
1. A matrix key input interface with a sink key matrix circuit, the sink key matrix circuit comprising: m (m is a natural number) key common signal lines and n+1 (n is a natural number) key data signal lines wired in a matrix; and m×n key switches connected between the m key common signal lines and a first to an n-th key data signal lines, the key common signal lines intersecting the key data signal lines, wherein a sneak preventing diode is connected between the n+1-th key data signal line and each of the m key common signal lines, the matrix key input interface further comprising: a monitoring unit that periodically monitors all of the n+1 key data signal lines while key scan signal is not output to any of the m key common signal lines; and a detection unit that detects an earth fault when any of the key data signal lines is at an L level while the key data signal lines are being monitored by the monitoring unit.