Sensing method and circuit of fingerprint sensor
A sensing method and sensor technology, which can be used in measuring electrical variables, acquiring/arranging fingerprints/palmprints, measuring resistance/reactance/impedance, etc., and can solve problems affecting measurement results, etc.
Active Publication Date: 2018-10-09
ELAN MICROELECTRONICS CORPORATION
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- Description
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Problems solved by technology
However, the measurement of the capacitance between the electrode plate 51 and the finger 60 will be affected by other factors. For example, when measuring the electrode plate Plate A, the electrode plate Plate A and its surrounding electrode plates Plate B~Plate The capacitance formed between D, and the capacitance C formed between the electrode plate Plate A and the protective electrode 52 (such as electrostatic protection electrode) FAS , will affect the measurement results
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[0046] Figure 1A and image 3 The first embodiment of the sensing circuit 10 of the present invention is described. The sensing circuit 10 includes a plurality of measuring units 11 and a control unit 12 . The measuring units 11 are respectively connected to the electrode plates Plate A˜Plate D.
[0047]The following description will take the electrode plate Plate A as an example to be measured. The measuring unit 11 connected to the electrode plate Plate A to be measured includes a first switching unit 111 and a readout circuit 13, and the measuring units 11 connected to the other electrode plates Plate B~Plate D respectively include a second switching unit 112a and A readout circuit 13 . The guard electrode 52 is connected to a second switching unit 112b.
[0048] Such as image 3 As shown, the first switching unit 111 includes a first terminal N 1a Connected to the electrode plate to be measured Plate A, and a second terminal N 2a Connected to the readout circuit 13....
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The invention discloses a sensing method and circuit of a fingerprint sensor. In the sensing method, a first to a third voltage are respectively applied to an electrode plate to be measured and a to-be-measured electrode plate in a first phase. The readout circuit of the electrode plate and a conductor adjacent to the electrode plate to be measured; then in the second phase, stop applying the first to third voltages, and apply a fourth voltage to the conductor, and connect the to-be-measured The measurement electrode plate is sent to the readout circuit, and the measurement result of the electrode plate to be measured is output by the readout circuit, and the measurement result of the electrode plate to be measured can no longer be affected by the method and circuit of the present invention. It is affected by the capacitance formed between the electrode plate to be measured and the conductor.
Description
technical field [0001] The invention relates to a fingerprint sensor, in particular to a sensing method and circuit of the fingerprint sensor. Background technique [0002] see Figure 12 and Figure 13 As shown, a schematic diagram of a projected capacitive fingerprint sensor 50 , which includes a plurality of electrode plates 51 arranged in a matrix, a guard electrode 52 , and a sensing circuit 53 connected to the plurality of electrode plates 51 . The sensing circuit 53 is used to detect the capacitance between each electrode plate 51 and the finger 60, for example, the capacitance C between the electrode plate Plate A and the finger 60 SA , the fingerprint image of the finger 60 can be obtained according to the capacitance between each electrode plate 51 and the finger 60 . However, the measurement of the capacitance between the electrode plate 51 and the finger 60 will be affected by other factors. For example, when measuring the electrode plate Plate A, the electrode...
Claims
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IPC IPC(8): G06K9/00
CPCG06V40/1306G01D5/24G01R27/26G01R27/2605H03K17/955G06V40/12
Inventor 杨昭锜
Owner ELAN MICROELECTRONICS CORPORATION