Cover Glass Grooves for Fingerprint Sensor Sensitivity
Solution Overview
Problem
The sensitivity of fingerprint recognition sensors in display devices is limited by material properties and strength degradation of the cover glass, which restricts the improvement of sensor performance.
Innovation Solution
A display device with a cover glass featuring first and second grooves and corresponding sensing electrodes, where the first grooves have a width and pitch in the range of several micrometers to tens of micrometers, and the second grooves cross the first grooves, enhancing the sensitivity by narrowing the distance between the finger and the sensing electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the permittivity of the cover glass is increased and the thickness is decreased to improve sensitivity, then the sensitivity of the fingerprint recognition sensor increases, but the strength and material properties of the cover glass degrade
Solution Approach 1:
The cover glass is segmented by forming grooves that divide the sensing area into multiple regions. These grooves allow sensing electrodes to be positioned closer to the fingerprint surface without requiring the entire cover glass to be thin, thus maintaining both sensitivity and structural strength.
Solution Approach 2:
The cover glass structure is modified locally by adding grooves at specific positions where sensing electrodes are placed. This local modification enables the electrodes to be closer to the fingerprint surface in the groove regions while the rest of the cover glass maintains its original thickness and strength.
2Measurement precision
If sensing electrodes are arranged significantly finely to recognize fingerprint ridges and valleys, then the measurement precision of the fingerprint recognition improves, but the device complexity increases
Solution Approach 1:
The sensing electrodes are arranged in a three-dimensional configuration by placing them within grooves that extend into the cover glass thickness direction. This vertical dimensionality allows for finer effective electrode spacing and better ridge-valley differentiation without requiring an overly complex planar electrode pattern.
Solution Approach 2:
The grooves act as intermediaries that position the sensing electrodes at optimal locations within the cover glass structure. This intermediary structure simplifies the electrode arrangement by providing predefined positions that naturally achieve the required measurement precision.
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 improves the sensitivity of fingerprint recognition by embedding sensing electrodes in the cover glass, allowing for more precise fingerprint detection and overcoming the limitations of traditional cover glass materials.
Implementation Method 1
the capacitive type fingerprint recognition sensor includes sensing electrodes arranged significantly finely to recognize a fingerprint according to a capacitance difference based on a distance between a ridge and a valley of the fingerprint
Data Source
AI summary
A display device includes: a display panel including a plurality of pixels; a cover glass on the display panel and having a plurality of first grooves; and a plurality of first sensing electrodes respectively in the plurality of first grooves. The plurality of first grooves have a shape on a plane corresponding to a shape of the plurality of first sensing electrodes.