The present invention relates to a fingerprint sensing device comprising a planar array of
closely-spaced capacitive sense elements. When a finger is placed in close proximity to the
sensing device, the capacitive sense elements measure a capacitance between the finger
and a single capacitor plate in each sense element. This is accomplished by precharging
each capacitor plate, and then using a known current source to remove a fixed amount of
charge from each capacitor plate. The measured capacitance varies as a function of the …

The present invention relates to a fingerprint sensing device comprising a planar array of
closely-spaced capacitive sense elements. When a finger is placed in close proximity to the
sensing device, the capacitive sense elements measure a capacitance between the finger
and a single capacitor plate in each sense element. This is accomplished by precharging
each capacitor plate, and then using a known current source to remove a fixed amount of
charge from each capacitor plate. The measured capacitance varies as a function of the …