Sensor Screen Integrating Touch and Fingerprint Sensing
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Solution Overview
Problem
Capacitive fingerprint sensors face challenges with increased size, complexity, and reduced touch sensitivity due to the need for high-resolution sensor arrays and integrated circuits, leading to overlapping with push buttons and increased bezel area, which affects fingerprint recognition accuracy and touch performance.
Innovation Solution
A sensor screen design with touch and fingerprint sensing electrodes arranged in a major and minor axis configuration, utilizing ground electrodes to reduce parasitic capacitance and electromagnetic interference, and a read-out IC for signal processing, which improves recognition accuracy by shielding neighboring electrodes and optimizing signal paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-resolution sensor array and IC are formed together using a silicon wafer, then fingerprint sensing capability is achieved, but device complexity and bezel area increase
Solution Approach 1:
The patent merges the fingerprint sensor and touch sensor into a single integrated sensor structure. The fingerprint sensor includes driving electrodes and sensing electrodes formed on a substrate, while the touch sensor uses the same electrode structure. This integration eliminates the need for separate fingerprint sensor assemblies and push buttons, reducing device complexity and bezel area while maintaining fingerprint sensing capability through capacitance measurement between the electrodes and fingerprint ridges/valleys.
2Area of stationary object
If push button and fingerprint sensor overlap, then space is saved, but thickness increases and fingerprint sensing area is limited
Solution Approach 1:
The patent transitions from a three-dimensional overlapping structure (push button above fingerprint sensor) to a planar two-dimensional structure where both touch and fingerprint sensing functions are achieved within the same electrode plane. The sensing electrodes and driving electrodes are arranged in specific patterns that enable both touch detection and fingerprint recognition without vertical stacking, thereby increasing fingerprint sensing area while reducing overall sensor thickness.
3Measurement precision
If separate fingerprint sensor and touch sensor are disposed, then specialized fingerprint sensing is achieved, but touch performance around fingerprint sensor deteriorates
Solution Approach 1:
The patent designs the sensor electrodes to perform multiple functions simultaneously. The same driving electrodes and sensing electrodes are used for both touch detection and fingerprint recognition. During touch mode, the electrodes detect touch position and force; during fingerprint mode, the same electrodes measure capacitance variations caused by fingerprint ridges and valleys. This multi-functional design ensures uniform touch performance across the entire sensor area, including regions that would otherwise be occupied by separate fingerprint sensors.
4Measurement precision
If ground electrodes are arranged between sensing electrode groups, then parasitic capacitance is reduced, but device complexity increases
Solution Approach 1:
The patent introduces ground electrodes as intermediary elements positioned between adjacent sensing electrode groups. These ground electrodes act as shielding elements that reduce parasitic capacitance and electromagnetic interference between neighboring sensing electrodes. The ground electrodes are connected to a common ground potential and are integrated into the existing electrode fabrication process, minimizing additional complexity while significantly improving signal quality and recognition accuracy.
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 design enhances touch and fingerprint recognition accuracy by reducing parasitic capacitance and electromagnetic effects, resulting in improved sensitivity and reduced bezel area, thus addressing the limitations of existing capacitive fingerprint sensors.
Implementation Method 1
ground electrodes arranged between neighboring touch sensing electrode groups and between a touch sensing electrode group and a fingerprint/touch sensing electrode adjacent to each other
Implementation Method 2
ground electrodes arranged between neighboring touch sensing electrode groups and between a touch sensing electrode group and a fingerprint/touch sensing electrode adjacent to each other to reduce parasitic capacitance and electromagnetic effects
Implementation Method 3
The capacitive fingerprint sensor utilizes a difference of electric charges charged between ridges and valleys of the fingerprint contacted thereto
Data Source
AI summary
The present disclosure relates to a sensor screen capable of recognizing a touch and a fingerprint. A touch screen includes an active area having a minor axis and a major axis intersecting each other, and a bezel area outside the active area. The touch screen includes a plurality of touch sensing electrode groups arranged in the minor axis direction, a plurality of touch driving electrode groups arranged in the major axis direction, a plurality of fingerprint and touch driving electrodes arranged in the major axis direction between the touch driving electrode groups, a plurality of fingerprint and touch sensing electrodes arranged adjacent to the outermost touch sensing electrode group from among the plurality of touch sensing electrode groups and a read-out IC arranged adjacent to the plurality of fingerprint and touch sensing electrodes.