QMatrix devices detect touch using a scanned passive matrix of electrode sets. A single QMatrix device can drive a large number of keys, enabling a very low cost-per-key to be achieved.
QMatrix uses a pair of sensing electrodes for each channel. One is an emitting electrode into which a charge consisting of logic pulses is driven in burst mode. The other is a receive electrode that couples to the emitter via the overlying panel dielectric. When a finger touches the panel the field coupling is changed, and touch is detected. The drive electrode (or drive line) used for QMatrix charge transfer is labeled as the X line. The receiver electrode (or receive line) used for QMatrix charge transfer is labeled as the Y line.
QMatrix circuits offer good immunity to moisture films, extreme levels of temperature stability, superb low power characteristics, and small IC package sizes for a given key count.