Touch-sensitive controls extend reach

摘要

Touch-sensitive controls are increasingly replacing electromechanical switches in home appliances and consumer and mobile electronics. Their popularity has gained momentum as designers have recognized that touch controls allow the creation of stylish and functional designs that differentiate products and create higher value for end users. Quantum Research Group developed and patented its charge-transfer sensing technology in 1999. Called QT, the technology is more stable than other forms of capacitive sensing and is more tolerant of electromagnetic interference, as well as of extreme and rapid changes in temperature and humidity. QMatrix uses a scanned, passive matrix of transverse electrodes to achieve a large number of touch keys driven by a single chip. Each sensing electrode pair contains a field drive electrode and a receive electrode. The emitting electrode is driven as a digital burst of logic pulses; the receive electrode normally collects most of the charge coupled from the emitting electrode via the overlying dielectric front panel.