| 摘要 |
PURPOSE: A fingerprint sensing method is provided to make an initial voltage of a fingerprint not have an influence on sensing the fingerprint, to output grey level value according to a fingerprint valley or a fingerprint ridge, and to detect electric characteristics of the fingerprint by scanning the fingerprint so that it can get detailed fingerprint distribution and reduce the number of sensing electrodes. CONSTITUTION: The method comprises steps of charging two or more capacitors to a certain voltage, distributing different charges to the capacitors according to the capacitance of the contacted capacitor when a finger is contacted, and measuring the amount of a voltage variation caused by the charge redistributed to the capacitors. When the capacitors are charged to a certain voltage, they are independent so that they are respectively charged to predetermined voltages. In the step of measuring the amount of the voltage variation, the independently charged capacitors are connected, and charges are differently redistributed according to the capacitance of the contacted capacitor. Two outputs at spatially adjacent points are compared and the difference between the two outputs is output in order to sense data on a grey level between a fingerprint ridge and a fingerprint valley as well as on the ridge and the valley.
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