Patent ID: 7099497
Filing Date: 2006-08-29
Classification: G06K

Abstract:
1. A capacitive fingerprint sensor, comprising: a capacitive sensing members array including a plurality of capacitive sensing members; an insulating surface layer covering over the sensing members array to serve as a contact surface for a finger; and a basic peripheral circuit, comprising: a row decoder arranged beside the sensing members array; a plurality sets of control lines inserted, in parallel, into the sensing members array and connected to the row decoder; a column multiplexer arranged beside the sensing members array and at a side perpendicular to the row decoder; a plurality of signal lines, which are vertically inserted into the sensing members array to intersect the control lines and is connected to the column multiplexer, wherein: each of the capacitive sensing members comprises a sensor structure and a signal reading circuit, the sensor structure includes a sense electrode, a reference electrode, and an insulating layer between the sense and reference electrodes, the signal reading circuit is arranged beside the sensor structure to connect the sensor structure to the corresponding control and signal lines, a sense capacitor is formed between the finger and the sense electrode, and a reference capacitor is formed between the sense and the reference electrodes; and the basic peripheral circuit repeatedly inputs, through the control lines: a set of the same first and second control voltages to the signal reading circuit for reset function to enable two terminals of the reference capacitor to have voltage difference and two terminals of the sense capacitor to have no voltage difference; and another set of the same third and fourth control voltages and a pulse control voltage to the signal reading circuit so as to enable the sense capacitor and the reference capacitor to share charges and to read the sense signals.