Fingerprint Identification Circuit Offset Compensation

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Solution Overview

Problem

Conventional fingerprint identification circuits have low accuracy due to inefficiencies in signal amplification and threshold voltage offset issues, which affect the reliability of fingerprint recognition in electronic devices.

Innovation Solution

A fingerprint identification circuit with an array of units, each comprising an input module, sensing module, source follower, acquisition module, resetting module, and output module, where the source follower amplifies sensing signals and the acquisition module adjusts potentials to cancel out threshold voltage offsets, improving signal identification accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional fingerprint identification circuit is used, then the device structure is simple, but the fingerprint identification accuracy is low

Engineering Contradiction:

Improvefingerprint identification accuracyVSAvoidcircuit structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The fingerprint identification circuit is divided into multiple independent fingerprint identification units arranged in an array, with each unit containing separate input, sensing, source follower, acquisition, resetting, and output modules. This segmentation allows each module to be optimized independently for accuracy while maintaining overall system manageability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The acquisition module performs preliminary action by acquiring and storing the threshold voltage of the source follower before the actual fingerprint sensing operation. This preliminary acquisition allows the system to compensate for threshold voltage offsets during signal processing, improving identification accuracy without adding complexity to the main sensing path.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If signal amplification is performed without threshold voltage compensation, then the circuit operation is simple, but the output signal accuracy is low

Engineering Contradiction:

Improveoutput signal accuracyVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system implements feedback by using the acquired threshold voltage information to compensate for offset errors in the source follower output. The threshold voltage data obtained during the acquisition phase is fed back into the signal processing chain to correct and improve the accuracy of the final fingerprint identification signal.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If the source follower is continuously active, then the signal amplification is continuous, but the power consumption increases

Engineering Contradiction:

Improvesignal amplification qualityVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The source follower is activated periodically rather than continuously, with distinct time periods for acquisition, resetting, and output operations controlled by separate control signals. This periodic activation maintains high signal amplification quality when needed while significantly reducing power consumption during idle periods.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically controls the operating state of the source follower and other modules, transitioning between active and inactive states based on the operational phase (acquisition, sensing, or output). This dynamic control optimizes the balance between signal amplification quality and power consumption by activating components only when required.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution enhances fingerprint identification accuracy by amplifying sensing signals and eliminating threshold voltage offsets, leading to improved recognition capabilities in electronic devices.

Implementation Method 1

The source follower is configured to, when the output control module is turned on, amplify the sensing signal and output the amplified sensing signal to the output module

Methodology Applied

Scientific EffectSource follower amplification:

Implementation Method 2

The sensing module is configured to sense a fingerprint and transmit a sensing signal to the source follower

Methodology Applied

Scientific EffectCapacitive sensing: Capacitance

Data Source

PatentUS10262180B2Fingerprint identification circuit, driving method thereof, and display device

Publication Date: 2019.04.16 BOE TECHNOLOGY GROUP CO LTD

AI summary

A fingerprint identification circuit includes a plurality of fingerprint identification units arranged in an array form. Each fingerprint identification unit includes: an input module configured to apply a detection signal to a sensing module; the sensing module configured to sense a fingerprint and transmit a sensing signal to a source follower; the source follower configured to amplify the sensing signal and output it to an output module; an output control module configured to apply an operating voltage for the source follower to the source follower; the output module configured to output the amplified sensing signal; a resetting module configured to reset an output end of the source follower and an input end of the output module to be at a first level; and an acquisition module configured to enable the input end and an operating voltage input end of the source follower to be electrically connected to each other.