TFT Fingerprint Sensor and operation method thereof

Abstract

The invention discloses a TFT fingerprint sensor and an operation method thereof. The fingerprint sensor includes a pixel array, each pixel including a switch and a pixel electrode for forming a capacitance with a fingertip. One or more active transmission electrodes are spaced from a selected row of the pixel array, and transmit a carrier signal into the finger without direct coupling into the selected pixels. Signals sensed by the pixel array are coupled to an independent integrated circuit, and connections between the IC and the pixel array are reduced by demultiplexing row select lines, and by multiplexing sensed column data. Differential sensing may be used to improve common mode noise rejection. The fingerprint sensor may be conveniently incorporated within a conventional touchpad LCD panel, and can mimic the performance of lower density touchpad pixels.

Description

technical field [0001] The present invention relates to an electronic fingerprint sensor, and in particular to a fingerprint sensor that uses a thin film transistor array to sense a user's fingerprint. Background technique [0002] Currently, conventional fingerprint sensors on the market use different methods to sense a user's fingerprint. A first type of fingerprint sensor consists of a complementary metal-oxide-semiconductor (CMOS) silicon chip with circuitry that provides an arrangement of many pixels. The CMOS silicon chip is covered with a protective coating formed from simple chemical coatings, wrapable substrates or other thin materials. This type of fingerprint sensor requires a silicon chip as large as the pixel array. [0003] The second type of fingerprint sensor includes metal lines formed on a substrate to form a pixel array, and a remote silicon chip is electrically coupled to the pixel array, wherein the size of the silicon chip is smaller than the pixel ar...

AI Technical Summary

Problems solved by technology

However, thicker protective coatings / surfaces create at least two new challenges: 1) As the thickness of the coverage increases, the signal strength from the transmitter to the finger and back to the receiver array decreases, which is typically increased the square of the distance (that is, doubling the coverage thickness, the signal strength will decrease by a factor of 4); and 2) depending on how the transmitted signal is generated, when the transmitted signal is transmitted from the transmitter to the receiver, the transmitted signal will obvious divergence

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