Optical Crosstalk Reduction in Fingerprint Display Sensors
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Solution Overview
Problem
In fingerprint identification display devices, the large distance between the finger and the light sensing unit due to encapsulation films and protective cover layers causes significant optical crosstalk, reducing the identification capability.
Innovation Solution
A surface texture identification display device with a base substrate and a contact plate, where pixel units include a light sensing component, a light converging component, and a light shielding component with a transmission hole, which converges and filters light to reduce crosstalk and enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encapsulation films and protective cover layers are added to protect the light sensing unit, then the light sensing unit is protected from damage, but the distance between the finger and light sensing unit increases causing optical crosstalk
Solution Approach 1:
A light shielding component with a light transmission hole is introduced as an intermediary element between the light converging component and the light sensing unit. This mediator blocks stray light while allowing focused light to pass through, resolving the contradiction between protection and precision by enabling the use of thicker protective layers without sacrificing identification accuracy.
Solution Approach 2:
The light shielding component creates a localized light transmission path through its light transmission hole, allowing light to pass only at the specific location where it is needed. This local quality approach enables precise light control in the region of the light sensing unit while maintaining protection in other areas, thus resolving the crosstalk issue caused by protective layers.
2Ease of manufacture
If the distance between the light sensing unit and contact plate is increased for structural reasons, then device assembly is simplified, but optical crosstalk increases reducing sensitivity
Solution Approach 1:
The light shielding function is extracted from the light sensing unit itself and implemented as a separate light shielding component with a light transmission hole. This extraction allows the light sensing unit to be positioned at an optimal distance for assembly while the separate shielding component compensates for the increased distance by blocking stray light, thus maintaining sensitivity despite the larger separation distance.
Solution Approach 2:
The light shielding component acts as an intermediary that compensates for the optical degradation caused by increased distance. By positioning this mediator between the light converging component and the light sensing unit, the system can accommodate larger separation distances for ease of assembly while maintaining optical precision through the mediator's light blocking function.
3Measurement precision
If a light shielding component with a light transmission hole is added, then optical crosstalk is reduced, but device complexity increases
Solution Approach 1:
The light shielding component is merged with the pixel structure by positioning it within the pixel region, specifically between the light converging component and the light sensing unit. This merging approach integrates the light shielding function into the existing pixel architecture rather than adding completely separate components, thus reducing the increase in device complexity while achieving crosstalk reduction.
Solution Approach 2:
The light shielding component serves multiple functions: it blocks stray light to reduce crosstalk, defines the optical path through its light transmission hole, and can be integrated with the pixel electrode structure. This multi-functionality reduces the need for additional separate components, thereby minimizing the increase in device complexity while achieving the desired optical performance.
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 device effectively reduces optical crosstalk and improves touch sensitivity by converging light onto a specific axis, allowing for accurate fingerprint or palm print identification even with a large distance between the sensing unit and the contact plate.
Implementation Method 1
a light converging component located between the light sensing component and the contact plate
Implementation Method 2
a light shielding component located between the light converging component and the light sensing component, wherein the light shielding component has a light transmission hole so that light passing through the contact plate and the light converging component passes through the light transmission hole to arrive at the light sensing component
Data Source
AI summary
A surface texture identification display device including a base substrate (10) and a contact plate overlapped with each other, the contact plate having a first surface configured to contact a textured surface, the first surface being located on a side of the contact plate facing away from the base substrate; and a plurality of pixel units located between the base substrate and the contact plate, wherein at least one of the pixel units includes a light sensing component on the base substrate, a light converging component located between light sensing component and the contact plate; a light shielding component located between light converging component and the light sensing component; wherein the light shielding component has a light transmission hole so that light passing through the contact plate and the light converging component passes through the light transmission hole to arrive at the light sensing component.