Fingerprint sensor and terminal device

Abstract

The invention discloses a fingerprint sensor and a terminal device, wherein the fingerprint sensor comprises an induction chip comprising an induction cell array, a first ground end and a first excitation signal source for providing a first excitation signal. Each induction cell comprises a detection electrode for forming detection capacitance among fingers of a user; a capacitance detection circuit respectively connected with the first excitation signal source, the detection electrode and the first ground end, and used for generating detection voltage based on the detection capacitance, the first excitation signal and a second excitation signal; and a second excitation signal source connected to the first ground end and used for providing a second excitation signal, the second excitation signal being synchronized with the first excitation signal. The fingerprint sensor according to the embodiment of the invention can improve the fingerprint detection accuracy, can thus improve the fingerprint identification rate, and has low requirements for package thickness and good applicability.

Description

technical field [0001] The invention relates to the technical field of fingerprint identification, in particular to a fingerprint sensor and a terminal device. Background technique [0002] In the fingerprint sensor, the detection of the fingerprint is realized by detecting the tiny capacitance formed between the surface of the finger and the sensing chip of the fingerprint sensor. Specifically, the excitation signal can be emitted through the external metal frame and received inside the fingerprint sensor to realize the detection of the fingerprint; it can also be emitted through the interior of the fingerprint sensor to make the sensing chip and the finger form a detection capacitance to realize the detection of the fingerprint . [0003] When the detection of fingerprints is realized by detecting capacitance, the fingerprints are distributed on the surface of the finger, and the fingerprint sensor is usually in the shape of a panel with an array of sensing units distribu...

AI Technical Summary

Problems solved by technology

Since the emission voltage is affected by the power supply voltage and the working range of the fingerprint sensor itself, the emission voltage is greatly restricted. The smaller the emission voltage, the weaker the signal detected by the fingerprint, which affects the detection accuracy;

[0006] 2. Susceptible to noise interference

The fingerprint sensor usually has a large surface area to fully collect the fingerprints distributed on the surface of the finger, but the large surface area can easily lead to large noise of the fingerprint sensor and errors in the manufacturing process, resulting in a decrease in chip performance;

[0007] 3. Package thickness is limited

Interference from adjacent sensing units such as figure 2 as shown, figure 2 The time sequence of each sensing unit emitting excitation (1-9) in the image 3 as shown, figure 2 The middle a is an array of fingerprint sensing units. When sensing unit b performs fingerprint detection, its adjacent sensing unit c is in a closed state, and the parasitic capacitance Cp between b and c interferes with b, reducing the accuracy of fingerprint detection.

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