US Patent 7545270 Capacitive proximity sensor with user

A sensing system for sensing the proximity of a part of a user to a control input, such as a control panel (14), for a vehicle subsystem (10), includes a transmitter (26) for transmitting a signal, a primary receivers (22) for receiving the signal via the user as a primary signal and a reference receiver (28) for receiving the signal via the user as a reference signal. One of the transmitter and primary receiver is associated with the user and the other with the control input (14). The reference receiver (28) is associated with the user and a controller (12) is provided to receive and process the primary and reference signals to provide a measure of the proximity between the part of the user and the control input (14).