Fingerprint Sensor Touch Screen Integration
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Solution Overview
Problem
Capacitive fingerprint sensors face challenges in size reduction and increased product cost due to the use of silicon wafers, and existing solutions that integrate fingerprint recognition with touch screens suffer from reduced sensitivity due to mutual capacitance and external noise.
Innovation Solution
A display device with a sensor screen that includes a first and second display area, where a fingerprint sensor and a touch sensor are strategically positioned between transparent substrates, and a timing controller divides the frame period to drive the sensors during display and touch periods, minimizing noise and maximizing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive fingerprint sensor uses a silicon wafer to integrate the IC with the sensor array, then the fingerprint recognition function is achieved, but the device size increases and product cost rises
Solution Approach 1:
The patent merges the fingerprint sensor with the touch sensor screen by integrating the fingerprint sensor array with the touch sensor electrodes in the same transparent substrate. This combination eliminates the need for separate silicon wafer-based fingerprint sensors, thereby reducing device size while maintaining fingerprint recognition functionality.
Solution Approach 2:
The touch sensor screen is designed to serve dual functions: touch sensing and fingerprint recognition. By making the touch sensor electrodes capable of detecting both touch events and fingerprint patterns, the system eliminates the need for dedicated fingerprint sensor components, reducing overall device size and cost.
2Reliability
If the fingerprint sensor is separately disposed in a portion of the screen area, then the fingerprint recognition function is achieved, but the touch performance around the fingerprint sensor is reduced
Solution Approach 1:
The patent combines the fingerprint sensor electrodes and touch sensor electrodes into a single integrated sensor system within the transparent substrate. This merging ensures continuous touch sensitivity across the entire screen area, including regions where fingerprint recognition occurs, thereby maintaining uniform touch performance without dead zones or performance degradation.
3Device complexity
If fine channels are configured to serve both touch group channels and fingerprint recognition channels, then the integrated design is achieved, but the mutual capacitance greatly increases
Solution Approach 1:
The patent segments the sensor operations into different time periods within each frame cycle. The fingerprint sensor is driven during specific periods when touch sensing is not active, and vice versa. This temporal segmentation allows both functions to share the same physical electrodes without mutual interference, maintaining sensitivity while achieving integration.
Solution Approach 2:
The system employs periodic switching between fingerprint sensing mode and touch sensing mode within each frame period. By alternately activating different sensor functions in time-divided slots, the patent enables both fingerprint recognition and touch sensing to operate on the same electrode structure without degrading measurement precision.
4Device complexity
If the fingerprint sensor is driven during the same period as the touch sensor, then the operation is simplified, but noise interference increases
Solution Approach 1:
The patent divides each frame period into distinct time slots: a first period for touch sensor operation, a second period for fingerprint sensor operation, and a third period for both sensors to be inactive. This temporal segmentation isolates the sensing operations, preventing noise interference between touch and fingerprint sensing while maintaining manageable operational complexity.
Solution Approach 2:
The system uses periodic time-division multiplexing where the touch sensor and fingerprint sensor are activated in alternating periods. During each sensor's active period, the other sensor remains inactive, thereby eliminating cross-talk and noise interference. This periodic switching maintains operational simplicity while effectively reducing harmful noise factors.
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
This configuration enhances the sensitivity and recognition rate of the fingerprint sensor while reducing noise interference, allowing for a more compact and cost-effective design.
Implementation Method 1
The capacitive fingerprint sensor utilizes a difference of electric charges charged between ridges and valleys of the fingerprint contacted thereto
Implementation Method 2
a capacitive touch sensor for identifying a fingerprint includes a touch sensor 403 including touch driving electrodes 401(x) and touch sensing electrodes 401(y)
Data Source
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AI summary
A display device and a method of driving the same are disclosed. The display device includes a display panel (DP) including a first display area (DA1) and a second display area (DA2) that are adjacent to each other, and a first touch sensor (TS) disposed in the first display area (DA1), a sensor screen (SS) disposed on the display panel (DP) and including a fingerprint sensor (FTS) and a second touch sensor (TS1-TS4) at a location corresponding to the second display area (DA2) of the display panel (DP), a display touch integrated circuit (DTIC) configured to drive pixels of the first and second display areas (DA1, DA2) and the first touch sensor (TS), and a fingerprint touch IC (FTIC) configured to drive the fingerprint sensor (FTS) in a portion of one frame period, in which the first touch sensor (TS) is not driven.