Display Device Touch Electrode Open Area for Fingerprint Sensing
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Solution Overview
Problem
Display devices face noise issues due to reflected light, particularly because touch electrodes are often formed between photo-sensing pixels and image display pixels, which can interfere with fingerprint sensing accuracy.
Innovation Solution
The design includes a display device with unit pixels that have a light sensing pixel and multiple display pixels, where touch electrodes are arranged to create open areas between the light sensing pixel and display pixels, preventing electrode overlap and thus reducing noise from reflected light. This configuration allows for improved fingerprint sensing accuracy by isolating light sensing and display functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If touch electrodes are formed between light sensing pixel and display pixel, then touch sensing coverage is improved, but noise from reflected light increases and fingerprint sensing accuracy deteriorates
Solution Approach 1:
The pixel array is segmented into distinct first pixel regions (for light sensing) and second pixel regions (for display), with touch electrodes configured to avoid overlapping the first pixel regions. This spatial segmentation allows touch electrodes to cover more area for touch sensing while preventing them from interfering with light sensing pixels, thereby resolving the contradiction between touch sensing coverage and fingerprint sensing accuracy.
2Adaptability or versatility
If touch electrodes are formed between light sensing pixel and display pixel, then touch sensing function is enhanced, but reflected light noise increases
Solution Approach 1:
The touch electrodes are configured with non-uniform distribution: they extend along the second direction with greater spacing in regions corresponding to first pixel regions (light sensing) compared to second pixel regions (display). This local quality variation allows the touch sensing function to be maintained in display regions while minimizing reflected light noise in light sensing regions, thus resolving the contradiction between touch sensing function and reflected light noise.
3Measurement precision
If touch electrodes surround first region and second region, then touch sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The touch electrodes are configured to simultaneously perform multiple functions: they surround both the first pixel regions (for light sensing) and second pixel regions (for display), enabling the same electrode structure to provide touch sensing coverage for both regions while maintaining uniform electrode characteristics. This multi-functionality approach improves touch sensing accuracy across the entire display area without requiring separate electrode configurations for different regions, thereby resolving the contradiction between touch sensing accuracy and device complexity.
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 arrangement effectively reduces noise caused by reflected light, enhancing the accuracy of fingerprint sensing in display devices by preventing electrode interference between light sensing and display pixels.
Implementation Method 1
The optical sensing may authenticate a user's fingerprint by sensing light reflected by a user's fingerprint
Data Source
AI summary
A display device includes unit pixels, each unit pixel including display pixels and a light sensing pixel, touch electrodes sensing a touch and, when viewed in a plan view, surrounding a first region where each of at least two display pixels is disposed and a second region where the light sensing pixel and one of the display pixels that is different from the at least two display pixels are disposed, and a main driving circuit receiving a light sensing signal from the light sensing pixel and sensing a fingerprint by analyzing the light sensing signal. The touch electrodes define at least one open area in which no touch electrode is formed between the light sensing pixel and at least one display pixel in each unit pixel.