A proximity detection apparatus for a control unit for use in controlling
a medical device, the proximity detection apparatus comprising: a
detecting part and an emitting part; one part being located in the
medical device and the other part in the control unit, so that when the
control unit is attached to the medical device the detecting part detects
the emitting part and instructs the control unit to select a first mode
of operation and when the control unit is detached from the medical
device, the detecting part does not detect the emitting part and
instructs the control unit to select a second mode of operation.