CAPACITIVE SENSOR APPARATUS AND METHODS

The touch panel module comprises a touch panel sensor element and a touch panel controller for measuring changes in capacitance associated with one or more sensor electrodes comprising the touch panel sensor element and generating corresponding touch panel output signalling is communicated to the host controller. The capacitance measurement circuit comprises a capacitance measurement channel coupled to a power supply line for the touch panel module, e.g., a ground for the touch panel module, and is configured to measure a capacitance associated with the touch panel module circuitry coupled to this power supply line and to generate corresponding capacitance measurement circuit output signalling for communication to the host controller. The touch panel power supply at the touch panel module is galvanically isolated from the capacitance measurement circuit power supply at the capacitance measurement circuit. Thus, the touch panel module may operate in a broadly conventional manner, whilst the capacitance measurement circuit simultaneously, or in a time multiplexed manner, measures a capacitance associated with the overall circuitry of the touch panel module, thereby providing a relatively sensitive proximity sensor.