Fingerprint Sensor Integrated Touchscreen Device With Separated Sensor Lines
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Solution Overview
Problem
Existing fingerprint sensor technologies face challenges in reducing capacitance connected to sensor lines, leading to decreased sensitivity in touchscreen devices due to high-density sensor packing, which increases the time constant of Tx channels and introduces noise in Rx channels.
Innovation Solution
A fingerprint sensor integrated type touchscreen device is designed with separated sensor lines for the touch and fingerprint sensor areas, using high-density sensor lines with independent driving mechanisms to reduce capacitance and improve sensitivity, allowing for simultaneous touch and fingerprint recognition without a dead zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-density sensor lines are used for fingerprint recognition, then fingerprint sensing capability is improved, but capacitance connected to sensor lines increases leading to decreased sensitivity
Solution Approach 1:
The sensor lines are divided into two separate groups: first sensor lines connected to touch sensors for touch recognition, and second sensor lines connected to fingerprint sensors for fingerprint recognition. This segmentation allows independent optimization of each sensor type without interference, resolving the contradiction between high-density fingerprint sensing and sensitivity maintenance.
2Adaptability or versatility
If dedicated fingerprint sensors are disposed in a separate region, then fingerprint recognition function is added, but a dead zone is created where touch cannot be recognized
Solution Approach 1:
The touch sensor area and fingerprint sensor area are merged into a single integrated sensor array where both touch sensors and fingerprint sensors coexist. The sensor lines are configured such that touch sensors cover the entire display area including regions where fingerprint sensors are located, eliminating dead zones and enabling both functions to operate simultaneously in the same physical space.
3Device complexity
If sensor lines for touch and fingerprint sensors are integrated, then device complexity is reduced, but capacitance increases leading to noise in Rx channels
Solution Approach 1:
Sensor lines are segmented into distinct groups: first sensor lines for touch sensors and second sensor lines for fingerprint sensors. This segmentation prevents capacitive coupling between different sensor types, reducing noise in the Rx channels while maintaining manageable device complexity through organized routing and connection schemes.
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 sensing sensitivity by reducing capacitance and noise, enabling accurate touch and fingerprint recognition across the touchscreen area without increasing the bezel size or thickness, thus improving user authentication and input accuracy.
Implementation Method 1
The capacitive fingerprint sensor recognizes the pattern of a fingerprint based on a difference in electric charge between the ridges and valleys touching the fingerprint sensor
Implementation Method 2
The optical fingerprint sensor scans a fingerprint by a light source such as LED (light-emitting diode) and detects the light reflected by the ridges of the fingerprint by a CMOS (complementary metal-oxide semiconductor) image sensor
Data Source
AI summary
A fingerprint sensor integrated type touchscreen device comprises a sensor array comprising a touch sensor area with sensors, a fingerprint and touch sensor area with sensors, sensor lines connected to the sensors in the touch sensor area, and sensors lines connected to the sensors in the fingerprint and touch sensor area. At least some of the sensor lines connected to the sensors in the fingerprint and touch sensor area are separated from the sensor lines connected to the sensors in the touch sensor area.