Capacitance reading circuit and fingerprint recognition system

Abstract

The present invention provides a capacitance reading circuit and a fingerprint identification system. The capacitance reading circuit includes a contact layer for accepting a finger contact; a shielding layer is arranged below the contact layer, and the shielding layer and The contact layer forms a parasitic capacitance; a driving circuit, coupled to the contact layer and the shielding layer; a sensing circuit, electrically connected to the contact layer, used for sensing at a second time the contact capacitor; and a first switch, one end of which is electrically connected to the shielding layer, and the other end is electrically connected to the driving circuit or the contact layer. The capacitance reading circuit and fingerprint identification system provided by the present invention can eliminate the effect of parasitic capacitance, and improve the accuracy and performance of capacitance sensing or fingerprint identification.

Description

technical field [0001] The invention relates to a capacitance reading circuit and a fingerprint identification system, in particular to a capacitance reading circuit and a fingerprint identification system capable of reducing the influence of parasitic capacitance. Background technique [0002] With the rapid development of technology, more and more portable electronic devices such as mobile phones, digital cameras, tablet computers, and notebook computers have become necessary tools in people's lives. Since portable electronic devices are usually used by individuals and have a certain degree of privacy, the data stored in them, such as phonebooks, photos, personal information, etc., are privately owned. Once the electronic device is lost, the data may be used by others to cause unnecessary loss. Although there is currently a password protection method to prevent the electronic device from being used by others, the password is easy to leak or be cracked, and has low securit...

AI Technical Summary

Problems solved by technology

However, there will be a parasitic capacitance between the contact layer and the shielding layer, and the capacitance value of the parasitic capacitance is often greater than the capacitance value of the contact capacitance caused by contact, which affects the capacitance reading circuit or the capacitive fingerprint recognition system to judge the capacitance value of the contact capacitance. As a result, the accuracy of fingerprint recognition is reduced

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