Touch Electrode Layout for Low-Noise Fingerprint Display Sensing
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Solution Overview
Problem
Light emitted from a light emitting part in display devices is reflected by a touch electrode and incident on an optical sensor, causing noise interference in fingerprint recognition systems.
Innovation Solution
The display device is designed with a touch sensing layer where the touch electrode is positioned closer to the light sensing part than the light emitting part, minimizing light reflection and reducing the need for additional light blocking members, thus simplifying manufacturing processes and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light blocking member is added below the touch electrode to prevent reflected light from reaching the optical sensor, then fingerprint recognition accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent converts the harmful effect of light reflection by strategically positioning the touch electrode so that its reflection pattern actually directs light away from the optical sensor. The touch electrode is positioned at a specific distance from the light emitting part and light sensing part, creating a geometric arrangement where reflected light is redirected to non-sensing areas, thus eliminating the need for additional light blocking members.
Solution Approach 2:
The patent changes the spatial parameters of the touch electrode positioning. Specifically, it sets the distance between the touch electrode and the light sensing part (first distance) to be smaller than the distance between the touch electrode and the light emitting part (second distance). This parameter optimization ensures that reflected light from the touch electrode does not reach the optical sensor, solving the noise problem without adding structural complexity.
2Object-affected harmful factors
If additional light blocking members are added to the display structure, then light reflection noise is reduced, but manufacturing cost and production complexity increase
Solution Approach 1:
The patent eliminates the need for separate light blocking members by utilizing the touch electrode itself as the light management element. By optimizing its position, the touch electrode's reflected light is redirected away from the optical sensor, converting a potential harm (reflection) into a beneficial arrangement that simplifies manufacturing.
Solution Approach 2:
The touch electrode serves dual functions: maintaining touch sensing capability and simultaneously acting as a light redirection element. This multi-functionality eliminates the need for dedicated light blocking components, reducing manufacturing complexity and cost while still preventing light reflection noise from reaching the optical sensor.
3Ease of operation
If the touch electrode is positioned closer to the light emitting part to improve touch sensitivity, then touch response is enhanced, but light reflection noise incident on the optical sensor increases
Solution Approach 1:
The patent optimizes the spatial parameters by setting the first distance (touch electrode to light sensing part) smaller than the second distance (touch electrode to light emitting part). This specific parameter configuration allows the touch electrode to be positioned for good touch sensitivity while geometrically ensuring that reflected light is directed away from the optical sensor, thus preventing noise interference.
Solution Approach 2:
The patent applies different spatial relationships to different components: the touch electrode is positioned at optimized distances relative to both the light emitting part and light sensing part. This local optimization of positioning creates a situation where touch sensitivity is maintained or enhanced while light reflection noise is simultaneously prevented from reaching the optical sensor.
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 effectively reduces light reflection on the optical sensor, enhancing fingerprint recognition accuracy while lowering production costs by eliminating the need for separate light blocking components.
Implementation Method 1
a plurality of light emitting parts on the substrate, and configured to emit light
Implementation Method 2
some of the light emitted from a light emitting part may be reflected by a touch electrode
Implementation Method 3
a plurality of light sensing parts on the substrate, and configured to sense incident light
Data Source
AI summary
A display device includes: a substrate; a plurality of light emitting parts on the substrate, and to emit light; a plurality of light sensing parts on the substrate, and to sense incident light; a bank layer partitioning the plurality of light emitting parts and the plurality of light sensing parts; and a touch sensing layer including a touch electrode on the bank layer. A first distance between one light sensing part from among the plurality of light sensing parts and the touch electrode in one direction is smaller than a second distance between a first light emitting part of the plurality of light emitting parts and the touch electrode in the one direction.